Wednesday, December 31, 2008

Understanding the performance/power curve of a PCP

by B.B. Pelletier

This final blog of 2008 was inspired by several questions from reader Kevin but also from other readers who are now owners of precharged pneumatic (PCP) airguns. I've written these things before, but perhaps never put them in the same order as I will today.

A PCP valve operates best between a certain high and low pressure point. That is to say the valve will open and remain open long enough to pass air from the reservoir to power a pellet to more or less the same velocity. When the reservoir pressure is high, it acts on the valve to close it faster, but the air that passes through the valve when the gun fires is under a lot of pressure. As you continue to shoot and the reservoir pressure drops, it acts with less force and less quickly on the valve to close it, so the valve remains open slightly longer. The air that passes through the valve before it closes is not pressurized as high; but since the valve remains open slightly longer, it delivers similar acceleration to the pellet. The result is that the pellet stays at the same velocity, more or less, throughout a number of shots.

The string of shots that are at the same velocity are the power curve of the gun. If the reservoir pressure is above the pressure at which this power curve begins, the shots will be slower. If the reservoir pressure is below the pressure at which the power curve ends, the shots will also be slower.

On either end of the power curve--before the curve begins (pressure too high) or after it ends (pressure too low), the pellets will exit the muzzle at a lower velocity than when the valve is dealing with pressure that's inside the power curve.

As a gun that has been over-pressurized is fired, it loses some pressure with each shot. The pellets will come out progressively faster as the pressure drops, and you can actually record this if you have a chronograph. Then, at some point the velocity seems to stabilize at a level of similar velocities for several shots. That area is the right pressure for your valve and therefore for your gun. We call that area the power curve because it represents the place within the whole pressure curve (zero psi to the maximum fill pressure) at which the rifle operates the best--and also at the same power (more or less).

As you continue to shoot and the pressure in the air reservoir drops below the ideal operating pressure, the velocity of the pellets starts dropping below the ideal range. The decline can be either a straight decline with each new shot or the velocity can go up and down, but it's always headed in a general downward direction. A powerful gun like the Career Infinity will usually drop velocity straight down with every shot when it falls off the power curve, while a less powerful gun like a Benjamin Discovery may have velocities that go up and down; but the general direction will always be down from the ideal level (the power curve).

So, with yesterday's 12-shot string that was continually declining with each new shot, I concluded that the rifle was coming down off the optimum power curve--a curve that would have been even higher than the 3,300 psi I put into the reservoir at the beginning. That's why I said this in yesterday's blog:

It seems as if the gun's maximum fill is still higher than 3,300 psi, but I don't have the pressure to go there. Nor do I think I would if I could. I've seen the walls of the reservoir, and they aren't that thick. I recommend you do not overfill this rifle, because I don't think there's a large margin of safety. I did it to demonstrate that the valve was not yet on the power curve.

Do you understand? My last sentence, "I did it to demonstrate that the valve was not yet on the power curve" refers to pressurizing the reservoir to 3,300 psi after testing the rifle at 3,000 psi. Since each shot declined in velocity with a 3,000 psi fill, I boosted the pressure to demonstrate that the velocity would go even higher. I'd hoped the first couple of shots would be close to the same velocity with the 3,300 psi fill, but you can see that they're not. Of course, that's not to say that 3,300 psi isn't the exact point at which the rifle drops off the power curve, and if I had pressurized the rifle to 3,400 psi I might have gotten those few close shots I was looking for. We'll never know, because I don't feel confident pressurizing this rifle any higher.

Kevin also asked why I said this--"the valve cannot function with pellets this heavy." I was referring to some guns that will never have a power curve with pellets over a certain weight. You didn't notice it because I didn't report the shot strings. When I went to the lighter pellets, I got some shots of similar velocities. That was with the power wheel set on the lowest power setting. The rifle is very clearly on the power curve with lighter pellets and a lower power setting.

So, Kevin, the velocities I saw told me that this Infinity was not on the power curve with Eun Jin pellets, but that it was very much on the power curve with both Crosman Premiers and Air Arms Diabolo Field pellets. With the lighter pellets, I manipulated the power adjustment wheel to keep the gun on the power curve longer.

Kevin asked what I meant by a "broad flat spot on a power curve." In this case, my answer looks better as a picture:

This is a typical velocity-over-pressure chart for a PCP. You get this by chronographing all the shots in a fill. If they look like this, you've captured the power curve, which begins at shot 15 (2600 psi) and ends at shot 27 (2150 psi). Filling this gun beyond 2650 psi is a waste of air, as is shooting after the 13th shot.

And, Kevin--every pressure above 2650 psi with this particular airgun is entering into valve lock.

Now you know it all!

Tuesday, December 30, 2008

Career Infinity by Shin Sung - Part 3

by B.B. Pelletier

Part 1
Part 2

Let's look at the Career Infinity velocity. The new inlet seal I showed you yesterday is working fine, and it may turn out to be the fix for this problem. I'll let you know at the end of the accuracy report, when the gun has been filled many more times.

You may recall that this gun doesn't shoot the pellets from the cylinders. It pushes them into the breech with a bolt probe, and that's where they are fired from. That way the long gap from cylinder to breech is a non-issue, as far as accuracy goes. The pellet begins its flight while already in contact with the rifling.

However, there are two observations I will make about the cylinders. First, they do not rotate far enough to align with the bore during the cocking stroke. After cocking, I had to advance the cylinder another half turn to get the pellet chamber aligned with the bore. You know that because the bolt probe won't align with the chamber in the cylinder, which prevents the sidelever from closing. That held true for both cylinders that came with the gun, and it takes away some of the speed you get from the rifle being a repeater.

The second thing I noticed about the cylinders is that it's possible to insert them into the receiver backwards, with the tails of the pellet pointed forward. If you do that, the pellets still feed into the barrel and still fire normally. Remember to load the cylinders with the outer spring to the rear.

Cocking is easy enough. It isn't exactly smooth, but the sidelever allows a powerful hammer spring to be compressed with reasonable effort.

The safety is, thankfully, manual. It's always there if you need it, but you don't have to fumble with it if you don't want to. It's easy enough to put on and take off with just the trigger finger.

There's a power adjuster on this rifle. There are four spots on the power wheel located in front of the triggerguard and there are a total of 12 positive click detents from lowest to highest power. Since that presents a lifetime of possibilities, I decided to limit the settings based on the pellet being used and how the air was holding out. With heavyweight Eun Jin pellets, I used the highest setting; with medium-weight Crosman Premiers and Air Arms pellets, I used the lowest setting.

Eun Jin
The Eun Jin pellet weighs 28.4 grains, nominally. With a fresh 3,000 psi fill, I got the following results with the first six shots:

985 fps
986 fps
965 fps
957 fps
949 fps
937 fps

That tells me the rifle is not on the power curve at 3,000 psi. It could also be that the valve cannot function with pellets this heavy. I then filled it to 3,300 psi and got these results:

1017 fps
1011 fps
1001 fps
998 fps
987 fps
979 fps

971 fps
962 fps
952 fps
944 fps
927 fps
924 fps

It seems as if the gun's maximum fill is still higher than 3,300 psi, but I don't have the pressure to go there. Nor do I think I would if I could. I've seen the walls of the reservoir, and they aren't that thick. I don't recommend overfilling this rifle, because I don't think there's a large margin of safety. I did it to demonstrate that the valve was not yet on the power curve.

Also, the way the valve is constructed, each shot will decline in velocity. This rifle has no broad flat spot on the power curve, like many PCPs do. However, I wouldn't shoot it this way if it were my rifle. Instead, I'd use the abundant number of lower-powered shots it offers.

Plenty of good shots at low power
On the lowest power setting, a fresh fill gave 6 strings of 6 shots between 927 f.p.s. and 1068 f.p.s. with 14.3-grain Crosman Premiers and 16-grain Air Arms Diabolo Field pellets. That's a total of 36 shots at that velocity range on low power from a single 3,000 psi fill. Taking a central 1,000 f.p.s. as the average for the 16-grain Air Arms pellets, that's 35.5 foot-pounds.

To get the last string, I bumped the power wheel up to the yellow level, which is three-quarters full power on this gun. The shots were still falling off rapidly, as you see here:

996 fps
983 fps
967 fps
954 fps
938 fps
927 fps

Maybe 30 shots is more realistic than 36, but that's a lot of very powerful shots with what may well turn out to be the most accurate pellets. As a practical hunting gun, you either get 12 shots that average about 60 foot-pounds or 30 shots averaging 36 foot-pounds. That makes the Infinity one heck of a good hunting rifle!

The single-stage trigger breaks after a lot of creep at a light 2 lbs., 10 ozs. The trigger blade is too curved for my taste, but I can't deny that it's lighter than the triggers of 99 percent of all unmodified rimfires.

There's a lot of intrigue to this rifle. Now that the inlet valve has been fixed, we're going to see what it's capable of. Next time, we'll look at accuracy.

Monday, December 29, 2008

Odds and ends Removing the Diana 27 seal & fixing the Infinity inlet seal

by B.B. Pelletier

It's too cold to shoot CO2 outdoors, so the accuracy test of the Crosman 1088 is postponed until we get some warmer days. So, I thought I'd clean up a couple of jobs that I'm working on and show them to you as I go. First, I removed the leather breech seal from the Diana 27 rifle.

Derrick found an inexpensive set of leather punches for me at Harbor Freight, so I ordered them to use in the Diana 27 breech seal project instead of just carving the seal from a leather belt with a sharp knife. There are nine graduated punches in the set for less than \$5, so even with shipping I figured it was well worth the investment. I'll probably have to trim the seal to final size, but the punches will get me most of the way there.

Today I decided to remove the old seal for you, so you can see what the job looks like. Several months ago, I bought a set of dental picks to use on the Walther Falcon Hunter breech seal I replaced during that test series, and they worked well for this seal, as well.

These picks were inexpensive, and they make handling breech seals easy. On this job, I had to break the seal into pieces and scrape it out of the channel.

Old seal was brittle
The old seal came out in chunks instead of a whole seal. That happens only
when the leather has lost all its sealing properties and has transformed into a waxy mass of dark stuff. It should have hung together, but the leather was shot. That happens when there's no lubrication for a long time--maybe decades.

When the old leather seal is completely removed from the Diana 27 breech, you can see the groove the new seal must fit. This photo is like an Escher print until you decode it in your mind. We're looking at a breech that's pointing up--away from us. The groove for the seal is wide and flat and there is a stub of the barrel in the middle. Notice that this shot shows more of the rifling, though a couple lands and grooves at 9 o'clock are invisible.

Weihrauch breech seal possible
Just for fun, I pressed a Weihrauch synthetic breech seal into the groove and it fit. It's about double the height it has to be for this gun, so I would have to divide it in half before installing, but I think it would work. But I want to try to fit a new leather seal to keep the rifle looking vintage.

I cleaned out the breech seal groove with the picks, so the groove is fresh for a new seal. A toothbrush was used to remove the smaller pieces of disintegrated leather.

That project is now on hold until the punches arrive, so I shifted over to the Career Infinity project. You'll remember that I replaced the inlet seal on my test gun, but then that seal started leaking, too. Boris made a Teflon seal to replace the brass seal holder in the gun.

Boris made the Teflon inlet seal on the left to replace the three-part inlet seal assembly that came with the rifle. Less mass may keep the seal from deforming too much.

The new seal is lighter and moves very smoothly inside the valve body. Being Teflon, it'll deform and take the exact shape of the valve seat. Hopefully, that'll fix the problem of the inlet valve dumping all the air after a fill.

When I filled the gun it held perfectly, but it also did that after the last seal replacement. The proof of the fix will be if the seal continues to hold after repeated fills, which I will be doing as we move into the velocity part of the test. Boris thought that the Teflon seal would be so light that it wouldn't get pushed out of shape like the brass carrier did to the factory seal. We shall see!

Friday, December 26, 2008

Diana 27 - Part 2

by B.B. Pelletier

Part 1

Today we'll look at my .177 Diana model 27 rifle after the piston seal and breech seal have been soaked in oil. I told you I put petroleum oil down the air transfer port because my gun is a low-powered springer with leather seals. Leather seals need lots of oil to keep them fresh and pliable, and a low-powered springer doesn't generate enough compression to detonate the oil. So, petroleum-based oil is fine for guns on this category.

The way to know for certain that you've oiled the piston seal enough is to move the barrel through the first few inches of cocking and then relax it. Do that several times and listen carefully to the air transfer port. When you can hear a slurping sound coming from the port, the piston seal is soaked with enough oil to rejuvenate it.

My .22-caliber model 27 that I tuned about 10 years ago with lithium grease on the mainspring still slurps when I test it, despite never having been re-oiled all that time. The excess lithium grease has soaked the seal from the back, making that tune a very long lasting one. However, I did use so much grease on the spring that I gave up some power with that rifle. I think when I tune this one I'll use black tar grease on the mainspring and oil the piston seal conventionally.

When I oiled the leather breech seal on this 27, it started to disintegrate. I took a closeup photo to show you what that looks like. This seal doesn't look too good to me, but looks can be deceiving. The chronograph test should tell us for certain if the seal still works. I cannot feel a blast of air coming from the breech joint when the rifle fires, which is one test for an air leak. But a chronograph test should be conclusive.

You can see the disintegration of the breech seal in this photo. Bits of leather are sloughing off, leaving pits where there should be a raised surface. An oil spray can be seen rising from the breech with every shot. Even though I can't feel anything, that oil spray confirms the fact that the breech seal is shot.

I also felt the barrel on this rifle deserved to be cleaned with J-B Non-Embedding Bore Cleaning Compound. Even though the velocity is not high enough for leading to be a problem with any pellet, we don't know the history of this rifle. If there's anything in the bore that could hurt velocity or accuracy (probably accuracy more than velocity), I want to clear it out. We'll start with a fresh new bore.

The bore seemed easy to clean, and there's a definite choke at the muzzle end. The breech was very dirty. After cleaning, all pellets loaded easier than they did during the first test. Now, let's see how the velocity is affected after oiling both the piston seal and the breech seal.

Eley Wasps
Before oiling Wasps averaged 444 f.p.s. After oiling and some sloughing of the breech seal, the average is 225 f.p.s. The breech seal is visibly leaking.

RWS Basic
RWS Basic pellets had averaged around 475 f.p;.s. before (they were very bi-modal, so I recorded two averages) and 212 f.p.s. after. The breech seal has failed.

Crosman Premier 7.9-grain pellets averaged 580 before and 321 after. In fact, only RWS Superdomes held anywhere close to their former average of 412 f.p.s., coming in close at 393 f.p.s.

Well, that wasn't a very big surprise, given the shape of the breech seal. The big question now is what does the piston seal look like. In my experience, leather breech seals fail sooner than piston seals, but we'll have to tear the rifle apart to know for sure.

The firing behavior has become rougher, which is the piston slamming into the end of the compression chamber because the air is leaking so badly at the breech. I hope I can save the piston seal, but a new breech seal is mandatory.

I adjusted the trigger, which is the rear screw only. The front screw is just a locking screw, and the rear screw controls how crisp and light the trigger pull is. I screwed it down pretty far, which made the second-stage pull very crisp. The drawback is a longer first-stage pull, but there's no way around it if you want a crisp second stage.

This photo is worth a lot to vintage Diana owners. The rear screw (at right) is down nearly all the way, and the front screw is tight. This gives a model 27 a crisp two-stage pull.

The next report will be either a disassembly of the powerplant or the repair of the breech seal, whichever comes first.

Thursday, December 25, 2008

Merry Christmas 2008

by B.B. Pelletier

Merry Christmas!

I was interviewed on the Arizona radio program, America Armed and Free last week. You can listen to that interview here, if you like. It will be available for one more week.

Today I'll share a couple of my favorite gifts with you, and maybe you readers can let us know what you got. For those who don't celebrate Christmas, you can either tell us about your most recent acquisition or just sit back and enjoy the party!

The man who has everything
What does Tom Gaylord's wife give him for Christmas--the man with the entire airgun world at his fingertips? While that's not entirely true, a lot of people think it is. They think I can have anything I want.

The truth is, I'm a lot like the rest of you. I do get to test a lot of exotic airguns and related stuff, but my own collection is based more on reality.

However, this year I asked for firearm reloading equipment. Now that my wife and I are shooting 100-200 rounds of .45 ACP every month, I can no longer keep up with my Lee 1000 turret press. So I asked for and received a Dillon Square Deal B press that makes 400-500 cartridges an hour without rushing. Instead of three hours of reloading I will now spend one hour at most to get better ammo than ever before! I also got a bunch of accessories that weren't included in with the press.

Dillon Square Deal B progressive reloading press makes up to 500 cartridges per hour with minimum effort.

I didn't receive any airgun gifts from the family this year, but I did get a peach of an aperture sight from reader Kevin, who wanted me to try it on a Diana 27. I plan to test it for you in a special report, but I wanted to show it to you today, because it is my one airgun gift this year. And isn't it sweet? My thanks to Kevin for this beautiful sight.

Kevin sent me this beautiful Diana aperture sight that will fit on a Diana model 27. It has a neat feature about it that Diana owners should know about. I will review it for you in detail.

I'm stopping here, but I want you guys to take over and tell us what you got. I'll be back tomorrow.

Wednesday, December 24, 2008

Buying a high-pressure air tank - Part 2 1000 posts!

by B.B. Pelletier

Part 1

Today's post is the thousandth since we began in March 2005. How fitting that it should come on Christmas Eve. Regardless of your religious views, we all owe Pyramyd Air thanks for their gift of this blog that has lasted so long. Let's hope we'll still be enjoying it after another thousand reports!

Lloyd wants me to tell you that you should buy the largest scuba tank you can afford. He also says to tell the dive shop operator to please fill the tank to the max, because divers are less concerned with pressure than we are. His most important message, though, is to get to know the people at your dive shop. I couldn't agree more. I've seen airgunners ruin their entire PCP arrangement by simply alienating the dive shop personnel. And I've gotten many concessions and good treatment because I acted as though the dive shop was doing me a favor--WHICH IT IS. A little civility goes a long way when dealing with an owner/operator, like the guy who runs the dive shop.

Lloyd also asks if dive shops are the only place to get a 4500 psi fill. Well, I think they are the WORST place! I go to a paintball shop, because my dive shop fills me to only 4,000 psi or so. That's all his air system can produce. Sometimes, you can get a fill from the local fire station. It helps if the firefighters are also airgunners or maybe you take them a couple dozen donuts when you go there. Like I said, some guys can do it and others can't. Ask yourself, "What would Wayne do?" when you go, and you'll probably get what you want.

Jony wants me to remind you that a smaller tank at higher pressure is often better than a large tank at lower pressure. The proof of that is the fact that a 2,200 psi tank won't even give you one fill of your AirForce Talon SS, despite being just as physically large as an 80 cubic foot aluminum tank that gets pressurized to 3,000 psi. In this game, pressure is king, and we either want tanks at higher pressure or guns that shoot at lower pressure. Having both is the best of all.

Pony tanks
A pony tank is a small air tank that divers and rescue workers use for convenience or for emergencies. We used them in the Army when fording rivers in our M60A1 battle tanks, because some of the crew members in the tank were 10 feet under water when the tank was driving across the river bed. If the air snorkel tube collapsed at those times, the driver could drown before he could get out of the tank. So, he used a pony air tank for a five-minute emergency air supply.

Big bore hunters carry carbon-fiber pony tanks to top off their rifles during a hunt. A small tank that fits in a backpack can refill even a large big bore rifle 2-3 times for a total of 6 additional shots. Any big-bore hunter will tell you that six shots is probably more than a day's supply for big-game.

When I competed in field target, I carried a 13-cubic foot pony tank to top off my Daystate Harrier. That rifle, which filled to 2,650 psi, got three refills from that little 3,000 psi pony tank. Since each fill was good for 24 shots, that was enough for almost 100 shots if you factor in the initial fill. A match typically has only 60 shots, so I was covered.

The Benjamin air tank is an example of a pony tank. Because it works on the Benjamin Discovery rifle which operates at 2,000 psi, it still gives plenty of fills.

Pony tanks have their place in PCP guns, but you don't want to buy one as your principal source of air.

Mr. B. says a day in the woods requires more shots than a Talon SS air tank can offer (maybe 35-45 shots at full power, depending on the range). Well, Mr. B., that Talon SS tank is actually a pony tank! Why not buy an extra AirForce standard tank? When your first one runs dry, just screw on a new one? That's how AirForce designed the gun to begin with.

Filling a gun from a tank
Abe asks about the proper way to fill a gun from a scuba tank, and I've had several other people ask the same thing. Here's a report I did on that subject. The first step is to connect the scuba tank to the gun. For this you need a fill adapter. One end connects to the scuba tank, the other connects to the gun. Both have to fit what they connect to, so you have to determine what it takes to do that. Scuba tanks and carbon fiber tanks have all kinds of valves. The most common scuba tank valve in the U.S. in the K-valve, but a DIN valve will sometimes be encountered. When the rated tank pressure goes above 3,000 psi, the DIN valve becomes more common. Your job is to determine what kind of valve your air tank has.

The K-valve is flat with an o-ring to seal it. This type needs a clamp that fits around the back of the valve to hold it.

A DIN valve has a hole with threads to accept any devices. This is the deeper 300-bar DIN hole, though both have the same diameter and threads.

A refill clamp fits around the K-valve.

Abe also asked about the scuba tank inspection process. That's not a part of this report, but I covered it here and also here.

Sooner or later, it'll dawn on you that a used scuba tank would be cheaper than a new one. But what you don't know is that there's a very good reason for that. A scuba tank must pass a hydrostatic pressure test every five years. When they fail or when they get near the end of their useful life, they aren't worth buying. We had a reader who bought a used tank for \$50, then had to spend \$135 getting it back in shape. While that was a little extreme (he needed a new K-valve), a hydro and the other tests you need could easily cost \$60. And you could wind up with a tank that fails its hydro, leaving you with nothing, because the testing facility will drill a hole in your tank to remove it from the market.

The best way to buy used is to buy from a dive shop you do business with. If there's a problem, they'll take care of you.

Tuesday, December 23, 2008

Diana 27 - Part 1

by B.B. Pelletier

Diana model 27 is a classic breakbarrel. My new one is a .177.

Kevin prompted this report by asking me about the Diana 27 I bought at this year's Roanoke airgun show. Then he surprised me with the gift of a very nice peep sight made for the Diana model 75. It also works great on the little Diana 27 rifles, and Kevin wanted me to see that so he sent one.

What I plan to do is test my new .177-caliber model 27 and then install the peep sight and test that for you. Unfortunately, the 27 I got in Roanoke doesn't have a rear sight base for this sight; I'll install it on my other 27, which is a Hy-Score 807 in .22 caliber. For those who are fascinated by coincidences, the .22 caliber Hy-Score was purchased from the same dealer from whom I bought the .177 15 years before. It was made in August of 1967, while the new gun was made in March of that same year. Spooky, no?

The new Diana came without a rear sight rail. The presence of the Diana logo indicates there never was one.

Many Diana 27 rifles, including this Hy-Score 807, have a rear rail like this for mounting a peep sight.

The top of the rail is textured with cross-slots that assist the peep sight by providing a solid anchoring surface.

I'll test the new rifle before lubricating the piston seal and again after a good oil soak. The oil will be applied through the air transfer port, so no disassembly is required.

However, I thought this new rifle would also be the perfect one to tune for you so I can show you the inside parts and how I tune it. That's coming some time in the future.

Before oiling
But right now, we'll test the rifle as I got it. The 27 is a low-powered spring-piston breakbarrel that was considered medium-powered in its day. The rifle had a long life, starting in 1910 and running off and on until 1986. However, all those model 27 rifles were not the same model. In fact, you can't really call them the same gun. The model 27 we're examining here started some time after World War II and finished in '86. That said, the final pre-war 27 rifle was quite similar in appearance to the post-war gun and differed only in the trigger and a few small details. This particular rifle I'm testing was manufactured in March 1967 (from the date stamp on the spring tube).

Eley Wasps
Kevin also sent along a tin of .177 Eley Wasps for me to test. He says they're very accurate in his 27, and he wanted me to try them in mine. The .177 Wasp is a domed pellet that weighs 8.1 grains on average. It's a pure lead pellet. In .22 caliber, the Wasp is also sold in an oversized 5.6mm, but in .177 the head diameter is 0.174" and the skirt is approximately 0.181" to 0.183". I say approximately because these pellets vary a lot. Being pure lead, they deform when handled.

They fit the breech of this rifle very tight and had to be pushed into the bore with a Bic pen to avoid damage to the skirt when the breech was closed. If I didn't seat them, the velocity was 278 f.p.s. Seated they had a velocity of 444, but it was sharply bi-modal with the lower average at 436 and the high at 460. There was no shot recorded between the velocities of 439 f.p.s. and 456 f.p.s. I suspect an extremely dry piston and breech seal.

RWS Diabolo Basic
RWS Diabolo Basic pellets were even more sharply bi-modal than the Wasps, with a low average of 457 f.p.s. and a high average of 512 f.p.s. No shot was recorded between 460 f.p.s. and 505 f.p.s. These pellets were also tight in the breech and had to be pushed into the bore with a Bic.

RWS Superdome
The RWS Superdome was not bi-modal and averaged 412 f.p.s. The high was 425 and the low was 395. They were also tight and seated in the bore with the pen.

Crosman Premier 7.9-grain
Crosman Premier 7.9-grain pellets could be seated by finger pressure alone. And they averaged 580 f.p.s., with a spread from 560 to 593. On paper, they appear to be a promising pellet, but the target will tell.

I had the feeling after this testing that the leather piston seal and breech seal need copious amounts of oil. So, I oiled the piston seal through the transfer port and the breech seal topically. I'll repeat this process one more time and give the rifle a couple days to soak it all in. Then, I expect the results to be faster and more uniform.

We shall see!

Monday, December 22, 2008

IZH-61 magazine test

Chuck is a reader who posted a lengthy comment about blind-testing a batch of IZH 61 clips. His methods were sound, so I asked him to turn it into a guest blog for everyone.

IZH-61 magazine test

by Chuck

I bought an IZH-61 for myself a while back and liked it so much that I bought one for each of my three grandkids. I had their 6 magazines and my 2 for a total of 8 magazines, so I developed a blind test.

I marked each gun and mag with each child's first initial in case a gun or mag got or lost so there'd be no arguing over whose it was. This made it easy for me to identify each magazine for the test, but only under close inspection because I used a black marker on the black mags.

Testing procedure
I assure you I did not know whose magazine I was shooting with, yet, after a batch of 8 magazines, I knew which magazine to match up with which target. Next, before shooting, I mixed up all the magazines and laid them out in the order of the targets. I then shot them in that order, matched and labeled them on their targets; I mixed them up again and shot another batch at 8 different targets. That was 2 batches of 8 magazines each, 5 shots per target, 16 targets, for a total of 80 shots, hence a fatigue and concentration issue. I had to concentrate harder on the second round of 8.

My range is indoors and 10 yards, I used the same Bug Buster scoped gun with Beeman H&N Match Wadcutters (8.0 grains). I used them because I had a lot, and I had previously weighed each one on an electronic scale.

Test results for batches 1 & 2
What I found was that a magazine that produced under 1/2" groups on the first batch of 8 magazines did worse on the second batch and vice versa. Of the 16 targets, all groups were 3/4" or better. Five were pretty close to 1/4". One magazine that did the worst on the first batch of 8 did the best on the second (must have been the pit stop).

The first 3 targets of each batch of 8 were inside 1/2"--I think due to my being more rested. The magazines that did not shoot inside 1/2" I re-shot after a rest period and got them inside a 1/2" (picture not shown so you'll have to take my word for it).

While shooting may not be physically fatiguing, it's definitely mentally fatiguing for me. I get what pro golfers call the yips, especially if I'm excited from shooting great groups. If you know any golfers, ask them about the yips. I'll bet you get shooters' yips, too.

The targets for each batch are numbered 1-8 and marked with the magazine numbers C1, C2, E1, E2, K1, K2, R1 & R2. The bullseyes on the targets are 1/2" in diameter.

Notice the strange location of target 8 (K2) on batch 1 (left target). Sorry for this sloppy batch, but I shot 2 warm up targets, then ran out of targets on this page so I aimed for the intersection of the lines formed by the block of four targets (2 practice--target 1 and target 3).

Note magazine R1 in batch 1 (target 5) has bad grouping while batch 2 (target 1) has good grouping. Next note that magazine K1 in batch 1 (target 6) has good grouping while batch 2 (target 5) has bad grouping.

Look at batch 2, target 4. Vertical stringing--that has to be me!

Test results for batch 3
The next day I did a similar test with just one batch of 8 magazines, but with a different pellet (no weighed). Ouch, I had somehow become a worse shot overnight. None of my groupings were as good as the night before. Three targets had fliers that went 2 or 3 rings out from center. Only one group was smaller than 1/2".

Test results for batch 4
I waited another day and tried the same test but this time with weighed pellets. I didn't have any radical fliers this time (or maybe they were all radical fliers) but all my groups were still larger than 1/2".

Wrap up
I then took 2 mags that had the worst groups and shot the same pellets with them. Still got bad groups. Well, you've probably guessed what my next test was. Yep, I went back to the H&N Wadcutters in those two mags and started shooting 1/4"-1/2" groups again. This doesn't necessarily mean the second brand of pellets are bad. It only means they're different for this gun or for me. I don't understand it, but it seems to be so. It could even be psychological if I think brand A is superior and my brain automatically concentrates better.

Conclusion
I believe my bad groupings in this test were due to lack of experience, shooter fatigue, lack of concentration, ill-spaced pit stops and/or pellet dynamics, and not magazine properties. When I gain more experience and find that pellet that is right for me and after my grandkids have broken in their magazines more, I will retry this test if for no other reason than my own amazement and amusement.

Post mortem
After completing my tests I took a close look at the mechanics of how the pellets are loaded into the gun barrel. In the IZH-61 owner's manual, Figure 1 shows a follower (item #8). It's a machined rod that is tapered toward the front, the part that goes into the receiver (item #44). The tapered part is about a half-inch long, smaller in diameter than the opening in the back of a pellet and is the part that rams the pellet into the receiver. The smaller rod also has a somewhat pointed tip that contacts the small indentation inside the skirt of the pellet to help guide it. The larger part of the rod is the diameter of the receiver opening. The rod is pushed forward when you cock the gun, and it shoves the pellet about 3/4" or so into the receiver because about 1/4" of the larger part of the rod goes in, too, to block any air blowback (I imagine).

It's my opinion that when the pellet is shoved into the receiver 3/4" by the rod, there won't be any influence on the pellet's orientation from the magazine at its final stopping position. However, I suppose a magazine could be defective enough to damage the pellet skirt in such a way that the movement into the receiver and down the barrel doesn't straighten it out. In that case, I think it would be easy to visually identify the defect.

You could argue that if a batch of magazines were bought, there's a chance one or more could be defective. However, at the same time, you could argue that one or more guns would have a defective magazine. I don't hear this coming from the multitude of IZH-61 owners (yet).

Bottom line
I had a whole lot of fun playing with this issue and fun is why I took up this sport in the first place. As an added bonus, I think I became a somewhat better shooter. I can't wait to see how a peep site will do on a test like this. Again, whoever it was who mentioned this in the first place, please come up with more thought-provoking ideas for me.

Friday, December 19, 2008

An outside-lock rifle by Gary Barnes

by B.B. Pelletier

Sorry for the size of this image, but I wanted to show you the whole rifle, and Blogger only allows photo widths of 5 inches. The butt contains the reservoir and is covered with leather.

In 1998, Gary Barnes built a rifle that I consider to be his masterpiece. It more or less conforms to traditional lines, through it has an extra-long 16.5-inch pull that makes it suitable for a giant. The gun is unusual in many ways. First, it is .25 caliber. While not completely unknown in antiquity, .25 is really a modern airgun caliber.

Next, the 32.75-inch barrel is rifled. Rifled outside lock guns are unheard of because they date to as early as the 1600s and not much later than the mid-1700s before rifling was in widespread use.

Other curious features are the sights. They're made from mammoth ivory, a material sometimes used by knifemakers as a way around the elephant ivory that's illegal today. This prehistoric ivory sometimes resembles modern ivory with the patina of age.

Finally, the rifle is made as a breechloader. That is almost unheard of in an outside lock, though not entirely.

The rifle breaks open slightly for loading. This is most unusual in an antique pneumatic gun.

This antler loader is for seating pellets deep in the breech, which increases the muzzle velocity.

What do we mean by OUTSIDE lock?
What is an outside lock? Well it's a novel way of getting around physical laws without building an air rifle with an outlandishly large action. The action parts are attached to the outside of the sideplate instead of the inside. That allows the mainspring to stick forward into space and therefore be several times longer than the receiver had room. And that means it can be more powerful--which is one key to the outside lock's performance.

The outside lock has most of its action parts attached to the outside of the plate. The hammer spring can be larger than the receiver because it doesn't have to fit inside.

A customer of Barnes had sent him a genuine outside lock from the early 1700s and asked for some repairs. While he had the lock, he disassembled it and looked at every part, then made the lock and gun you see here. The lock he made looks remarkably similar to the original, and it functions exactly the same. Barnes made all the parts, including every screw that you see here. He made a trigger similar to the original but with one difference. His trigger ends in the center of the action and is usable by shooters who are either right- or left-handed.

Barnes lock at top and antique lock below. Barnes made the spring for the antique.

How does it work?
The outside lock is a marvel of engineering, because it is NOT a knock-open valve. Instead, it's the first true timed-release valve. The valve isn't knocked open. Instead, it's pushed open by a lever. That's why the mainspring has to be big and strong to overpower the valve and open it against the stored pressure. And this timing of the valve is another key to the gun's performance.

How are valves "timed"?
Once the valve opens, the hammer holds it open as it swings to its stop through an arc. If you look at the Barnes lock in the above picture of the two locks, you'll see a cam on top of the lever that pushes on the valve. It's at the top of the lever, which is located to the left of the hammer. When the hammer is cocked, it passes that cammed lever and swings way back to the left edge of the action. When the gun fires, the hammer passes the other lever, hitting that cam and pushing it forward at the top, which pushes it backwards at the bottom. The hammer and lever remain in contact for a long time as their two cams slide over each other, which holds the valve open longer. This is how they achieved the timing of the valve.

This drawing is scanned from Airgun Revue #4. The descriptions were removed because they're unreadable at this size and resolution, but you can see how the hammer interacts with the valve striker through the cams.

And what does a timed lock do?
The power of this gun depends on the shape of the two cams, the power of the hammer spring, the power of the valve-return spring, the size of the valve port, the air pressure inside the reservoir and the length of the barrel. The longer the valve is held open, the more pressurized air can flow out. The longer the barrel on the gun, the more time it has to act on the pellet. So, a timed lock also needs a long barrel to achieve its full potential.

Barnes' first hammer spring developed about 22 foot-pounds on a 600 psi fill, but it broke during operation. The second spring he made produced over 28 foot-pounds on a fill of 800 psi. That's right--just 800 psi and I got 12 shots from the gun. The first three were above 700 f.p.s. and the 12th shot was 462 f.p.s., when shooting a 20-grain Diana Magnum. A Beeman Kodiak would have almost certainly pushed the rifle over 30 foot-pounds, but the Diana Mags were the most accurate. Here are the exact velocities of all 12 shots:

713 f.p.s.
792 f.p.s.
795 f.p.s.
664 f.p.s.
635 f.p.s.
606 f.p.s.
581 f.p.s.
557 f.p.s.
539 f.p.s.
518 f.p.s.
495 f.p.s.
462 f.p.s.

The first shot illustrates a little bit of initial valve lock. My guess is the fill pressure is really best around 700 psi, but adding the extra 100 psi is not that harmful. However, it looks to me like another 100 psi would drop the velocity quite a bit, because that first shot is significantly lower than the second one. In the time before chronographs, the shooter relied on his ear and on bullet performance to indicate when to stop. Based on that, 10-12 shots seemed to be the limit.

Accuracy was about 3/4" for five shots at 10 meters. That was measured edge to edge across the widest dimension of the group. Because this is .25 caliber, it's actually a half-inch group. Not too shabby for open sights and a barrel that's nearly a yard long!

Alas, I no longer own the outside lock rifle. It was sold several years ago and is now in another collector's care. But that's how the world works. You never really own the vintage airguns you have. They're just yours for a time and then they pass on to someone else. If you think about it, that's how you came to acquire them in the first place.

Thursday, December 18, 2008

Buying a high-pressure air tank - Part 1

by B.B. Pelletier

This report is for Abe, but with the large number of folks coming into precharged airguns, I suspect many people need to read it.

When I started in precharged pneumatic guns (PCP) in 1996, the need for air was not as critical as it is today. The problems back then were overcoming the personal fears of high-pressure air, getting dive shops to fill the tanks for non-certified persons and, of course, adapters.

The adapter problem continues to be bad, though there are movements to standardize at Crosman, Daystate and in the aftermarket. But the tanks themselves are more critical now than ever before. That's because the guns of today need more air than they used to.

Size doesn't matter
Here is the problem. The physical SIZE of the scuba tank means next to nothing. What MATTERS is how much air it holds. You say, "Of course!" But until you become a PCP user, you don't really understand what that means.

The most common scuba tank
The standard scuba tank today is an aluminum 80 cubic-foot tank that's pressurized to 3,000 pounds per square inch (psi). The physical tank measures just under 30 in. high by about 7 in. in diameter. It weighs just under 40 lbs. when filled (mine weighs 38.5). All these specifications will vary slightly from manufacturer to manufacturer.

The most commonly used scuba tank in the U.S. is the 80 cubic-foot aluminum tank.

And it will completely fill a PCP rifle that needs 3,000 psi one to three times, depending on the volume of the gun's reservoir. AirForce rifles that have a huge 490cc air tank get about two complete fills from such a tank. Remember, I'm now talking about complete fills to 3,000 psi.

After a full fill come partial fills
After that, the rest of the fills will end at less than 3,000 psi, because the scuba tank's pressure has dropped. Taking an AirForce Condor as an example, each successive fill could look something like this:

2975 psi
2925 psi
2870 psi
2850 psi
2815 psi
2755 psi

And so on for about 15-18 fills. When the pressure in the scuba tank drops below 2200 psi, there isn't enough air left to fill the AirForce tank high enough to get the gun on the power curve. That means you have to get the scuba tank refilled.

Actual results will vary
The actual number of gun fills you get varies, based on how low you allow the gun's tank to decline before refilling and the size reservoir you're filling. So the numbers I've just given are approximations. Don't try to create mathematical formulae based on them--they're just general observations.

Get a bigger tank
If you want more fills, the solution is to get a tank that holds more air. In the scuba tank world there are aluminum tanks rated to hold 100 cubic feet of air at 3300 psi and steel tanks rated for 120 cubic feet of air at 3500 psi. Obviously, these tanks will give you more complete fills of any PCP than the 80 cubic-foot aluminum tank. The 100 cubic-foot aluminum tank is larger than the 80 cubic-foot tank, but the 120 cubic-foot steel tank is about the same size as the 80 cubic-foot aluminum tank. The 3500 psi steel tank weighs about five pounds more than the 80 cubic-foot tank. Both of these larger tanks cost more than the 80 cubic-foot tank. You have to look for sales when buying tanks like this.

Smaller is more
Then there are the tanks made of carbon fiber. They're actually aluminum bladders wrapped with carbon fiber fabric. They seem to be contradictions, because they're smaller and lighter than 80 cubic-foot aluminum scuba tanks, yet they hold more air. My 88 cubic-foot tank is 24 in. by 7 in. and weighs about 20 pounds when filled to 4,500 psi. It will completely fill the AirForce reservoir perhaps 7 to 9 times and will get many more partial fills than an 80 cubic-foot scuba tank. It costs several times as much as an 80 cubic-foot tank. So, as with most things, you pay for performance.

Carbon fiber tanks are rated to hold breathing air, but for land operations. They are most often encountered in rescue service operation.

So far, all I've talked about are the largest portable air tanks. That makes what I'm about to say meaningful. If I were shooting a big bore rifle that gets two or three shots per fill and needs 3,000 psi to be completely filled, an 80 cubic-foot tank would be inadequate. The tank that most smallbore PCP owners use today could not supply the air needed to keep a big bore operating very long.

But if I had a Benjamin Discovery rifle that has a maximum fill of only 2000 psi, an 80 cubic-foot scuba tank would be great! I would get a great many full fills and lots more partials from that tank. That's why I pushed hard for the 2000 psi fill level when we developed the Discovery. Besides being easier to fill with a hand pump, it extends the use of scuba tanks many times.

Okay, Abe, that's the first part of the report. Next week I'll cover smaller scuba/carbon fiber tanks, tank valves and buying used. What I need YOU to do is ask me questions now so I can work the answers into the next report. The same goes for all readers who have questions.

Wednesday, December 17, 2008

Crosman 1088 - Part 2

by B.B. Pelletier

Part 1

Before I begin, here's an update on the Career Infinity. I wanted to test velocity for you today, but when I picked up the rifle it had leaked off a little, so I topped it off with the scuba tank. When I bled the line to disconnect from the tank, the inlet valve stuck open and exhausted all the air again. This was the same problem the rifle had before and fixed in the last report.

I called Boris at Pyramyd Air, and we talked about the problem a bit. Boris told me he has seen this happen a couple times. What's happening is that the inlet valve isn't returning to the exact spot it was before it opened, so a small passageway remains open for air to escape. The soft valve material allows that to occur. He thinks a Teflon valve may solve the problem because it would be lighter than the brass valve body that's in the gun now, plus Teflon conforms to almost any surface with a minimum of fuss. He's getting a new Teflon valve out to me. I will let you know how well it works when I get it installed.

Today, we'll look at how the Crosman 1088 pistol performs for velocity. The temperature outside is 27 degrees F, but in my office it's a toasty 70 degrees.

The first discovery is that it's best to remove both grip panels to load a CO2 cartridge. You need to gain access to the screw key, and the grip panels get in the way. Yes, I applied Crosman Pellgunoil before piercing the cartridge.

I think I discovered why owners are tightening their cartridges too tight and causing leaks after a while. This gun loads silently. You cannot hear the gas rushing in. I finally stopped when I knew I had turned the key enough (really too much) and sure enough there was gas in the gun. For some reason, this is a quiet gun. Probably due to a new seal at the piercing pin. At any rate--watch it!

Crosman Silver Eagles
Let's get the speed-demon pellets out of the way. Crosman Silver Eagles went an average of 440 f.p.s. in double-action and 410 in single-action. The pellets I used were not the hollowpoints that weigh 0.2 grains less, so there might still be more velocity in the gun.

Beeman Kodiaks
Somebody asked me to try Beeman Kodiaks for accuracy in this pistol, so I also clocked them. They averaged 291 f.p.s. in double-action with a spread from 283 to 306. Single-action was 277.

No single-action
At this point, I discovered that the 1088 does not like to be fired single-action. At least the test gun doesn't. The hammer is only for firing. When you cock it, the clip doesn't advance to the next chamber. Only the trigger advances the clip. Several times the hammer released before the clip rotated, and I either shot a blank or I tied up the gun's action. I have to recommend you don't shoot it any way but by pulling the trigger. The Crosman website states the gun can be shot DA or SA, but the manual states that you fire the gun by pulling the trigger and does not mention cocking it with the hammer. We've emailed Crosman to get the facts on this. I'll update you when I find out.

RWS Diabiolo Basics
RWS Diabolo Basic pellets averaged 324 f.p.s. They ranged from 317 to 328.

Benjamin Sheridan Diabolo domes
Benjamin Sheridan Diabolo domes (7.9-grains.) went from 353 to 322. They score an average of 335 f.p.s. That's odd, since they're nearly a full grain heavier than the Basics that went 11 f.p.s. slower, but that's what happened.

Crosman BBs
The 1088 is also a BB gun, and, as a reader pointed out to me in the first report, a magnet holds the Crosman Copperhead BBs in the clip instead of the ridges down the inside of the chambers that I mentioned in my report. The BBs averaged 368 f.p.s. and ranged from 388 down to 348. However, they exhibited the same drop in velocity, shot after shot, that the pellet did. When shooting the BBs, I took pains to allow only five seconds between shots. Here's what that looks like:

388
386
371
367
361
358
348

Then, I waited a full minute before shooting the last shot.

353

The velocity drops with every shot when a five-second interval is used between shots. That means this gun is very sensitive to temperature. So for accuracy, wait at least 15 second between shots. It'll probably still hit pop cans at 20 feet when fired fast, but the groups will open on paper.

There seem to be 50-60 good shots per cartridge, which is about what we expect for this kind of performance. There are many lower-powered shots after that, so you need to be mindful of stopping before you jam the gun.

Remember what I said about not tightening the cartridge too much when you pierce it. I think that will prevent the leaks some shooters report after owning the gun for a while.

Tuesday, December 16, 2008

How a spring-piston airgun works

by B.B. Pelletier

Today I'm writing an emergency blog I shoehorned into the list. Sparkie, who assures me he is NOT Clark W. Griswold Jr. (Chevy Chase's Christmas Vacation), sent me a comment with his interpretation of how a spring-piston airgun worked. He was off a little, as many people are, so today I will show you exactly how a spring-piston gun works.

The spring-piston airgun is the simplest type of powerplant from the standpoint of parts. There are but a few. It's a wonder that it's also one of the most recently developed, but read this report to see the history.

The gun works by the force of a piston compressing the air in front of it to power a pellet. A powerful spring or charge of compressed gas drives the piston when the gun fires. Besides a spring, in the past both dynamite and gunpowder have been used to power the piston. On the back page of the January 2009 edition of Popular mechanics, there's a brief piece about a gas-powered gun NASA uses to test micrometeor impacts. That gun is powered by gunpowder that compresses hydrogen gas to 100,000 psi. That gun has no piston, so the sabotted projectile acts as the piston instead. Interesting!

No matter what type of spring-piston mechanism it is (breakbarrel, underlever or sidelever), the barrel aligns with an air transfer port like this when the gun fires. The air transfer port is shown at the right of the picture. These parts are in front of (to the left of) the compression tube shown below.

They all work the same
All spring-piston guns have a spring-powered piston (some have more than one) inside a compression chamber. That chamber connects to the barrel through an air transfer port. When the gun is cocked, the piston is withdrawn into the compression chamber, and air is drawn through the transfer port.

Inside the compression tube, the piston rests against the front of the compression chamber until the gun is cocked.

Here's the secret!
This is what confuses a lot of people. Inside the compression tube, which is also called the spring tube, the piston rests at the end of the tube until the gun is cocked. The air transfer port is at the end of the compression tube and leads directly to the barrel. There's no valve of any kind in this system. It's like a soda straw that you can blow through to expel a paper ball. No valve is required.

When the piston's withdrawn, it pulls air into a chamber that forms in front of it. That chamber is called the compression chamber. There's nothing mechanical between the piston and the barrel, where the pellet sits.

When the piston is withdrawn upon cocking, a compression chamber forms in front of it. After that chamber lies the air transfer port and after that is the barrel.

When you load a pellet into the barrel, it forms an airtight seal. When the barrel is plugged with a pellet, the piston goes forward and compresses the air in front of it and the air presses hard on the pellet until it overcomes the pellet's resistance. The pressure of the compressed air is high--above 1,200 psi in tests that have been done. But the AMOUNT of air at that pressure is very small--just what was in the compression chamber.

So, the pellet gets swatted on its tail by a tiny puff of air at very high pressure. The pellet cannot remain where it is, so it starts moving down the barrel. As it does, the air behind it loses pressure rapidly. After 8-10 inches, the air is almost at the same pressure as it is outside the gun. The pellet has accelerated to as fast as it will go by this point.

That's all there is to it
There's nothing more than that at work in a spring-piston airgun. There are different designs of powerplants, of course, but they all work by the same simple design. In a Whiscombe rifle, two pistons that are opposed come together like the clapping of hands, with the air transfer port at the center of where they meet. But the operation of the piston(s) doesn't change.

Back in the 1960s, Jack Lewis, a noted gun writer and editor, saw a cross-section drawing of a spring-piston rifle and assumed that the blank space occupied by the air transfer port was a reed valve. He proceeded to describe the operation of that valve in great detail in his article about how a certain spring gun worked. The only problem was that THERE WAS NO VALVE!

What I am showing you here is all there is to this design.

Sparkie and anyone else who wants to learn more about how spring-piston guns work--here are two recommended posts. Both are multi-part reports.

The air transfer port

Spring gun tune

Monday, December 15, 2008

2008 Long-range Airgun Silhouette Shooters Organization shoot (LASSO)

by B.B. Pelletier

Last Saturday, I attended the 2008 LASSO shoot on the Boyd Farm in Lavon, Texas. They have 1,000 acres of grazing land and generously allow Eric Henderson to host the shoot on one of the lower pastures. This shoot is for big bore airguns.

The targets are half-sized steel silhouettes of rams placed roughly at 100, 150, 200, 250 and 300 yards. This year I believe they ranged between 107 and 300 yards because several shooters measured them with laser rangefinders. The two closest targets that were 107 and 170 yards have round steel plates that fall out when hit. A shooter can aim to knock these plates out of the target and get extra points.

Before the shoot, Dennis Quackenbush (dark blue on the top right) makes several announcements to the shooters.

The winds was ferocious! Gusts were hitting 40 m.p.h. and the average wind from 9 o'clock was 20 m.p.h. While those big bullets weigh more than smallbore pellets, they can't buck that kind of wind out to 300 yards, so allowances had to be made.

Speaking of smallbores, some local shooters showed up with some smallbore PCPs and set up a range of their own off to the side. They were there to see what the big bores were all about, but they had some impressive guns of their own--including a BSA Super 10 that was so quiet all I heard was the hammer dropping. It shot 10.5-grain Premiers at 940 f.p.s. and could hold a reasonable group out to 50 yards despite the wind.

Wayne--here's a guy who shoots like you. No recliner, though.

Every year I try to notice the theme of the shoot, and this year it was advancement. Instead of just buying guns and shooting them, I saw shooters who were taking the technology into their own hands and developing things not seen before. One of these was a sidelever that took only a few ounces of effort to open and close. It was so smooth that it used a magnet to hold the handle in the closed position to prevent it from opening under its own weight.

This clever sidelever needs almost no effort to open.

One pair of shooting buddies arrived with all the creature comforts, including an ATV to ferry them around the grounds. There was a rack for rifles built into the bed, and it was clear these guys took their hobby most seriously.

These guys know how to live!

Another shooter had a Buntline pistol that got two shots at an identical 660 f.p.s. That's pretty fast when you consider he's shooting a 500-grain slug! An air pistol that generates 484 foot-pounds of energy at the muzzle is a big deal! I will show it shooting in the video I'm compiling.

David enjoys his .308 pistol so much that he bought a companion at the LASSO meet. He shoots with open sights.

Other shooters had variations of Quackenbush big bores they had taken to new heights. There weren't as many Korean guns there this year, but several key shooters who normally use them failed to attend for various reasons.

This man sights-in his new Quackenbush .50 ball shooter after purchasing it from another shooter at LASSO.

LASSO host Eric Hernderson gets into a prone position to shoot his Quackenbush .308.

You can't shoot these guns without air. Since they get 2 to 4 shots per fill, that means a LOT of air. Eric had his compressor, and everyone was filling their carbon fiber tanks throughout the match. A typical rifle may get 40-60 shots per tank, so a compressor is a good thing to have. Eric's unit was busy most of the time filling many carbon-fiber tanks to 4500 psi.

Eric's compressor supplied all the air the shooters needed.

As the day progressed, the wind increased in force to the point that the competitors had something major to contend with come contest time. I had to leave before the match was finished, unfortunately, because my kidney stones were acting up. But there will be a LASSO again next year and several airgun shows before it to acquire that big bore. Is 2009 the year you want to get in on the fun?

I'll also be writing an article and making a video soon, so this isn't the last you have seen of this event.

Friday, December 12, 2008

How I learned to love guns

Before I turn today's blog over to my wife, I have an announcement. Tomorrow the LASSO big bore airgun shoot will be held outside Dallas, Texas. I will be there to photograph things for you and also to conduct an experiment. Dennis Quackenbush dreamed this one up after reading all the conjecture about maximum velocities on the forums. He has constructed a testbed airgun that will shoot super-lightweight projectiles in an attempt to set the speed record for a PCP airgun. His gun has barrels in .25 and .375 caliber, so we will see the results of two different guns. They're smoothbores, of course, because velocity is the only thing we're testing.

I will report the results next week.

If you live near Dallas and want to see what big bore airguns are all about, visit this website:

LASSO '08

Now, on to today's blog.

How I learned to love guns

by Edith "Mrs. B.B." Gaylord

March 23, 1983, we moved into the first house we ever owned. We'd been living in my apartment after getting married the previous May. We each brought something to the marriage...I brought 8 house cats, Tom brought guns.

A couple days after we moved in, the previous homeowner stopped by with a housewarming gift and some chit-chat. As she walked out the door, she said, "Oh, yes, you've got mice." Nice parting words! Actually, I didn't have any fear of rodents, plus I was quite certain our cats could take care of them. Although they were house-bound cats, their hunting instincts were still intact. Well, sort of.

If you know anything about cats, you know they enjoy playing with their food. And, if the food's alive, even better! I clearly remember the first time our cat Dizzy brought the first live mouse up from the basement. The minute he put the mouse on the floor, the other 7 cats gathered around and formed a circle...what I call a "coven of cats." Tom quickly grabbed the Sheridan Blue Streak, loaded and pumped it, and yelled for me to move the cats out of the way so he wouldn't shoot them. Tom finally got a clear shot and quickly dispatched the mouse.

I soon realized that Tom wouldn't always be home to eliminate rodents, so I asked him to show me how to shoot the Sheridan. After several training sessions, I was ready for bear...I mean mice. We hung a yellow twist tie off the gun's triggerguard so I could distinguish it from the other rifles. Plus, that reminded me to grab the yellow plastic box of pellets, which were the most accurate. Over the years, I used our trusty Blue Streak to dispatch a number of mice, one snake outside the basement door and several rats that had moved into the planter outside the front door.

In time, I learned more about firearms and airguns (and even airsoft guns). The only reason I was able to enjoy guns was due to Tom's non-threatening, non-macho way of introducing them to me. He wasn't trying to impress me with anything. If they're in the house, whether they're airguns or firearms, I should know how they work, how to use them, how to load them and what type of ammo they use.

Fast forward 25+ years, and we now have our concealed carry permits. While I know how to shoot all the airguns, I don't know how to load and shoot all the firearms because I haven't had the time to go to the outdoor range. However, I DO know how to load and shoot all the self-defense guns. And I'm not afraid to use them. Every couple of weeks, we go to an indoor range and shoot our .45 autos. It's the caliber of my carry gun, and I love it!

Tom has done such a good job of teaching me about guns, that I now encourage him to buy almost any gun he wants. Recently, I suggested that he buy another gun. Know what he said? "I think I have enough for right now. Maybe next year."

Don't you wish your wife encouraged you to buy guns? If you introduce her to guns with the right attitude and the right guns, she just might!

Thursday, December 11, 2008

Comparing regulated and unregulated airguns

by B.B. Pelletier

Mr. B. requested this one--comparing regulated precharged pneumatics to unregulated PCPs.

What is a regulator?
First, what is a regulator and how does it work? A firing valve in a PCP does not operate at its peak at 3,000 psi--not even close. Most of them work best down around 2,000 psi and some work best at even lower pressure. But, the fact is that they still do work acceptably well at higher pressure. So, the gun gives a string of shots at a more or less constant velocity until it drops below the lowest pressure at which the valve functions well.

Valve lock
Just above the top-end operating pressure, the valve starts closing sooner than it should. When a certain pressure is exceeded, the gun begins to shoot slower than it's capable of shooting. It continues to do this until the internal pressure drops below the point where valve lock starts happening.

An air valve has a range of pressure--from low to high. As long as the air that's supplied to it stays within that range, the gun shoots at a constant velocity, more or less. And it's the "more or less" that's of great concern to airgunners.

An unregulated gun
I have a Daystate Harrier that operates best between 2650 psi and 2,000 psi. In that range, I get 24 shots of 10.6-grain Beeman Kodiaks going about 920 f.p.s. They will not vary more than 20 f.p.s. throughout the entire range. But fill to 2700 psi, and the pellet might go only 880 f.p.s. for the first two or three shots. Continue shooting after the 24 good shots (pressure falling below 2000 psi), and the velocity drops again into the 800s.

That is what a fairly good unregulated gun will do. I've seen better ones that would keep their strings within 10 f.p.s. throughout the range. All valves are not of equal quality and stability. I've also seen valves that varied more throughout their range. The AirForce Talon SS will often vary by 30 f.p.s. throughout its range, yet still shoots half-inch 5-shot groups at 50 yards.

A regulated gun
What about a regulated gun? Well, a regulator lowers the pressure of the reservoir to an ideal level before making it available to the valve. You might want to read my report on the air pressure regulator. If I installed a regulator in the reservoir of my Harrier, I could probably drop the velocity variation within the string of shots from 20 f.p.s. down to 10 f.p.s. or, perhaps, even less. I've tested PCP guns that varied by only two f.p.s. throughout their entire string of usable shots.

However, by installing a pressure regulator with its firing chamber inside the reservoir of my Harrier, I'd be subtracting volume from the reservoir. In other words, less room for air. That could be offset by increasing the pressure in the reservoir, but there's a point beyond which the regulator will not operate. So you can't just keep increasing the pressure indefinitely.

What are the benefits?
How would I benefit if I installed a reg in the Harrier? Well, quite probably I would pick up a shot or two. Experience shows that with small reservoirs, like the one in the Harrier, a reg will add only a shot or two to the total string. And all the shots would be closer in velocity because the firing valve would be working at the ideal pressure. The question I have to answer is if I think it's worth a couple extra shots and a slightly tighter velocity variation to go to the trouble of installing a regulator.

I decided that it wasn't, because my Harrier operates at a nice low max pressure. It's easy to pump to 2650 psi; much easier than to pump to 3,000 psi. At least, it is for me.

On the other hand, my Career 707 went from 30 usable shots to over 60 at the same power with a regulator. And the velocity variation of those shots dropped from over 30 f.p.s. to around 10 f.p.s. In that case, it was definitely worth the effort to install the reg.

Some things to consider
Some guns aren't suited for regulators. The AirForce guns, for example, cannot be easily regulated because of how their tanks are made. Any regulator would have to be external to the tank, which would add to the rifle's length of pull. The Benjamin Discovery has a small reservoir like the Harrier, so adding a regulator might not gain an advantage in total shots, but it might tighten the extreme spread of the string, which is on the order of 30-35 f.p.s. right now.

The final thing I want to say about regulators is they will all fail at some point. That's a fact that cannot be denied. I'm not talking about decades of time, either. Regs are not known for lasting a long time. The greater the pressure differential (difference between reservoir pressure and firing pressure) they must deal with, the shorter their life tends to be. When they go, you usually end up with an unregulated gun. In some cases, you have a broken gun that has to be repaired to work at all.

The USFT
For that reason, Larry Durham decided not to regulate the design of what became the USFT rifle. He felt it's better to have an easily repairable rifle than to have a super-tight velocity spread. The USFT won the 2007 Field Target World Championship.

Here are my personal feelings. I like regulators on 10-meter guns, where they seem to last a long time. But on a sporting airgun, I like an unregulated but balanced valve that I know will outlast any regulator. However, when the reg is working, it makes for a wonderful airgun experience. I cannot deny that.

Wednesday, December 10, 2008

Career Infinity by Shinsung - Part 2

by B.B. Pelletier

Part 1

This is part 2 of the Career Infinity report. Normally, I'd be testing velocity, but something came up. Today I'm going to take you on a short excursion inside a gun, to show you a little about how they work and also how easy they are to repair.

You see, when I tried to fill the test rifle for velocity testing last week, the inlet valve wouldn't accept air. Then, at around 3,000 psi, the inlet valve suddenly popped open and accepted a fill of about 1,000 psi inside a few seconds. It seemed clear that the inlet valve was sticking.

When I tried to bleed the fill clamp, the air never stopped--a sure sign that the inlet valve was now refusing to close. So, the rifle lost its entire fill. I then sat looking at the gun for many minutes, trying to decide what to do next. That's not unlike what many of you would do when something similar happens. Normally, I would have boxed up the rifle and shipped it back to Pyramyd Air, but this time I noticed that the design of the Infinity inlet valve is quite simple and straightforward, as though it was built to be repaired. I partially disassembled it and saw that it was as simple as I had imagined, so I thought this time I would fix it myself and let you see what's involved.

A call to Boris at Pyramyd Air got me the parts I needed. They turned out to be a simple o-ring and the inlet valve seal. We'll do velocity next time (which won't be long now that the rifle is fixed).

The inlet valve body is aluminum and very straightforward. It screws into the air reservoir tube and two o-rings seal it. Taking it off required one 10" channel-Lock pliers and a leather belt to keep the jaws from marking the valve body. Everything came apart easily, and I confirmed that the inlet valve seal was the cuplrit.

I'm going to show you the rebuild in pictures.

The reservoir tube awaits the inlet valve body.

We're looking at the reservoir side of the inlet valve body. This deep hole is where the valve parts go.

The valve body contains these three parts. A brass holder holds the inlet valve seal (left). This is the bad seal that I will show you when I remove it. In the middle is the inlet valve return spring. On the right is the threaded keeper that holds these parts inside the inlet valve body.

Here we see the old seal (right) and the new seal installed in the brass holder. The seal isn't supposed to have that deep groove in the center.

Here I've dropped the new seal in its brass holder into the valve body.

And now the return spring is dropped into the hole.

The keeper is the last part to be installed. Once it's threaded in the hole, the inlet valve assembly is complete.

Now the valve body is screwed back into the reservoir. Both o-rings around the outside of the body (one shows here) have been lubricated with diver's silicone grease. The body threads into the reservoir by hand until this o-ring makes contact.

To screw in the valve body the rest of the way, channel-lock pliers are used with a leather belt in their jaws to prevent marks to the aluminum valve body. You make very small movements this way because of the barrel, but there isn't much to do.

The valve body is installed. Now it's time to install the barrel hanger and the inlet port.

The inlet port (shown upside down so you can see the seal) is now screwed into the valve body.

The inlet port is back on and the barrel hanger is attached. This job is done!

Are we done?
I aired up the rifle to 2000 psi and it held fine, so this job is done. Start to finish was probably an hour, but the reassembly seen here took 30 minutes with the photography. Writing the blog took a lot longer.

Why did I show this to you? Because in all honesty, things like this happen sometimes. I knew this one was simple, and I wanted to show you what that means. The keys here are cleanliness and lubricating with silicone grease.

Tuesday, December 09, 2008

A brief history of spring-piston airguns

by B.B. Pelletier

This one is for Airdog.

Spring-piston airguns are one of the newer types of powerplants, coming into being about 1840. The first spring-piston guns were long guns that used volute springs instead of helically coiled springs to drive the piston. Take your belt and wind it into a tight coil on a flat surface like a table. Then pull on the center of the belt and it will rise, creating a conical spiral. The flat belt will now be an elongated spiral with a wide end and a narrow end. That is the shape of a volute spring.

Instead of leather, the springmaker starts with a flat steel bar that he winds into a flat coil, just like the belt. The last move is to stretch the spring by pressing the center upward. Once it takes that form, it's hardened and becomes springy.

Volute spring started out as a flat steel bar.

You wouldn't think springs made that way would be very good, but they are. The suspension of an M60 battle tank relies on volute bumper springs as the final shock absorbers--for the time when those 61 tons come crashing down to the end of travel for its main torsion bar suspension. So, volute springs can take a lot of stress! To make them longer, they're sometimes placed in line, and the double volute spring is a most common type found in antique airguns.

This Buegelspanner, or "triggerguard-cocker," is a common pattern airgun made from the 1850s to the 1890s--maybe later. It uses a double-volute mainspring to power the piston.

By the 1870s, coiled steel or helical springs were being used in Quackenbush and some German spring-piston airguns. Up to this point, all the guns used a flat leather seal on top of the piston. The guns were not very powerful and velocities ranged between 200 f.p.s. and 400 f.p.s. The diabolo pellet was still over three decades in the future, so darts and solid lead slugs were the projectiles used.

1872 Haviland & Gunn spring-piston air pistol my wife bought for \$5 at a local flea market. It shows the typical arrangement of the powerplant that was housed in the grip.

German Eisenwerke push-lever lock spring-piston long gun used a coiled steel mainspring.

Air RIFLE!
Up to the year 1900, airguns were chiefly smoothbore. So, the long guns are correctly called guns and not rifles. In 1905, the Birmingham Small Arms company, better known today as BSA, decided to add airguns to the firearms they had made for almost a half-century. They decided on a design created by Lincoln Jefferies--an underlever that was loaded through a rotating tap. The barrel was rifled, and the first guns made were called H The Lincoln air rifles. They were made for Jefferies, but BSA wanted to make more rifles than Jefferies could sell, so they worked out an agreement whereby they could also produce the model under the BSA name.

The air rifle that started it all was made by BSA in 1905.

This was the first modern spring-piston air rifle, and all that have come since have used design details that were present in this first gun. Within a very few years, the first diabolo pellets were being sold and increased the accuracy of the new air rifle dramatically. In that day, it was considered a wonderful thing for the air rifle to group five shots in one inch at 50 feet.

From 1905 until 1980, the spring-piston gun continued to improve in velocity and to get synthetic piston seals, but not really to change in a dramatic way. Then, another significant change was introduced.

Major innovation: the gas spring
I'm not certain of this next part, but all my research indicates that the Argentine company that makes Shark airguns was the first to put gas springs into spring-piston rifles in the early 1980s timeframe. Very soon thereafter, Theoben of the UK rose to dominance with a complete line of refined gas-spring rifles. Some of those Theobens set velocity records when they first came out. Vortek, an American company, came along in the late 1990s with drop-in gas spring conversions for several popular rifles.

Not an innovation but a perfection
In the mid-1980s, Weihrauch brought out the HW77, which quickly rose to fame as the No. 1 field target competition rifle in the UK. Aftermarket tuners did a hundred tricks to improve the already fabulous action of this fine underlever, until it was thought to be the pinnacle of spring-piston airguns. And, then, Air Arms upstaged it.

The TX200 was all that the HW77 was, plus it had something the German rifle didn't--a concentric barrel-piston axis. With that one innovation, the humpbacked underlever shot ahead of its Teutonic rival to become the best spring-piston air rifle the world has ever seen...except for the guns of John Whiscombe.

The Air Arms TX200 was the most advanced spring-piston gun when it came out in the late 1980s, and it's still a leader today.

Whiscombe and Park
Working quietly in his shop, Whiscombe has been turning out handmade spring rifles for several decades. His guns are underlevers with a difference. They have dual opposed pistons that come together like the clapping of hands. When they do, their force is cancelled, giving the rifles a trace of vibration but no recoil. Perhaps they represent the high-water mark of the spring-piston evolution. A decade ago, another maker called Park attempted to put the dual opposed piston into semi-production status, but they didn't last too long. Their rifles are very smooth and recoilless, but cost considerably more than a TX200 during their production years.

What comes next?
Where we're headed is anyone's guess. The current trend for ever-faster rifles is hitting a wall, but the sales are so brisk that makers won't stop competing for top honors anytime soon. Oddly, no spring-gun maker in the world has seen the one niche in the market where there's no competition at all--the smooth-shooting plinker. Thirty years ago, there were plenty of easy-cocking plinkers on the market, but they've almost vanished. Gamo has the makings of one in their Whisper, but they don't know what to do with it. So they sell it on the basis of velocity and the "silencer" on the end, ignoring the attributes of light weight and easy cocking.

The Chinese are poised to make a perfect plinker, but they're so focused on everything Europe is doing that they'll never be able to get out of their own way. Therefore, the Chinese-made Hammerli 490 will continue to have a heavy trigger and lose sales from an adult market that laments the passing of the Diana 27. Mendoza is also close with their RM-200 rifle, but they don't understand the importance of easy cocking.

And the HW30/Beeman R7 has priced itself right out of the market it is so perfectly created to dominate. I think the next big thing in spring-piston air rifles will be the return of the accurate, easy-cocking plinker. It's a gun that never should have gone away, but the velocity wars have obscured its importance.

Said differently, for every R7 that's sold, Daisy sells a thousand Red Ryders. Not that the Red Ryder is what people want, but the idea of a light, convenient airgun is universally appealing.

Monday, December 08, 2008

by B.B. Pelletier

Part 1 - Under \$25
Part 2 - \$50 and under
Part 3 - Under \$100

First, I'd like to thank all of you who wished me well with my kidney stones. My wife is heavy into alternative medicine, so as soon as I complained about a backache she started her diagnosis. In the past, I've had a chronic bad back, so I tend to ignore back pain. This has been going on for over a month, so there was a lot to remove.

She started me on a mixture of lemon juice and olive oil taken three times a day. The morning I complained on the blog was the start of the third day, and the treatment had started to work. That evening I started passing stones and parts of stone without pain. The next morning my back pain was reduced by 90 percent and life was almost back to normal.

Several of you also sent me other natural cures and I tried them all. After all, they are just food, so the worst that can happen is nothing changes. At any rate, life is getting back to normal for this 61-year-old, and I wanted to thank you all for your concern.

Today, I am doing the final installment of my Christmas Gift Guide. Like the first three, not everything on this list is a personal favorite of mine, so I will indicate when something really is a favorite. These things cost more money, and I'm going to insert a little more opinion with them.

Airguns
TX200 Mark III This one is a personal favorite of mine and I know that anyone who gets one will be very satisfied. Before anyone asks, I'm not recommending the Hunting Carbine or the Pro-Sport, although I know people who are very happy with both guns.
Air Arms S410 sidelever This rifle is loved by so many shooters, including Wacky Wayne, the high priest of the 410.
Air Arms S200 Again not a favorite of mine, but so many airgunners love this rifle that I have to list it.
AirForce Condor A personal favorite of mine, this powerful precharged rifle has a style that some love and some do not.
AirForce Talon SS Another personal favorite. Get an optional spare 24" .22 cal. barrel and you have a second rifle that's two-thirds the power of a Condor.
RWS Diana 460 Magnum If you want a magnum spring rifle, this is about the best one I know of. Because it's an underlever, it isn't as hold-sensitive as a breakbarrel. The power is great for a springer.
RWS Diana 350 Magnum If you want a magnum spring rifle that's a breakbarrel, this is the best one in its power class, in my opinion.
RWS Diana 34 Panther A personal favorite of mine for an entry-level spring rifle.
Gamo Whisper with Air Venturi gas spring Here is another favorite of mine, but only in .177 caliber.
Beeman HW77 carbine A personal favorite of mine, the HW77 ruled the world before the TX200 came along.
Beeman R7 A perfect plinker. Get it in .177 and never let it go.
Beeman R1 Another time-proven favorite. I would put this rifle ahead of the RWS Diana 350 Magnum in all ways, except the RWS is more powerful. I like this one in .22 caliber.
Beeman R9 I'm including the R9 because I must be the only person on the planet who doesn't like it. A very popular spring rifle with the same power as the R1 in a smaller package.
Benjamin 392 A proven classic pneumatic air rifle. The 397 is just as great in .177 caliber.
Benjamin Discovery You KNOW I like this rifle! It has everything I want in an entry-level PCP. Either caliber is good; get it with the pump unless you know the reason to do otherwise.
Crosman 2250XE
Daisy 853 A great little target rifle at a decent price.
Daisy 499 World's most accurate BB gun. I own one and highly recommend it.
Evanix Renegade rifle A refined AR-6. Very usable.
Beeman FWB 700 If you can afford it, one of the two best 10-meter rifles in the world.
Mendoza RM200 Best low-priced spring rifle available today. I like .22 but get either caliber.
Beeman P1 Top spring pistol.
Benjamin HB17
Benjamin HB22
Benjamin EB22
Beretta 92FS
Colt 1911
Crosman 2300S The Crosman 2300S is a good one, too.
FWB P44 target pistol
Gamo Compact pistol
IZH 46M target pistol
IZH Drozd pistol
Desert Eagle pistol Super accuracy and blowback action.
RWS Diana 5G Magnum pistol
S&W 586 revolver
Walther CP88 pistol
Walther CP99

Airsoft
Taurus Raging Bull revolver
TSD Luger pistol
Walther P38 pistol
WE M92 pistol
Shadow Ops Type 96 sniper rifle
Echo 1 M249 machine gun
Echo 1 designated sniper rifle
UTG M4 An AEG built in the U.S.A.!
Thompson M1A1

Scopes
Leapers 8-32x56
Leapers 4-16x56 scope
Hawke 6-24x50 scope
Hawke 4-16x50 scope

Friday, December 05, 2008

Crosman 1088 - Part 1

by B.B. Pelletier

I was asked by several people to review the Crosman 1088. In fact, I think the requests date back over a year. I thought this was just a modern extension of the 1008; but, where the 1008 is mostly metal on the outside, the 1088 is mainly plastic.

This is an 8-shot CO2 pellet and BB pistol with a revolving action housed in a pistol frame. The steel barrel is rifled, so we can expect some accuracy from pellets. Owners rate it above 4 stars, which is a good indication that it's worthwhile.

Being plastic, the gun is light...just over a pound. The grip is quite large, so the gun feels large, yet the double-action trigger-pull is very light and smooth.

A CO2 cartridge fits inside the right grip, which pops off the gun. The winding key that tightens the cartridge is enclosed by the grip, so nothing shows from the outside.

Pop off the right grip panel to install a CO2 cartridge.

To load the 8-shot clip, the slide is flipped up at the back, exposing a pin that the circular clip sits on. The clip is loaded by pushing pellets or BBs in the back side, and you can load either one without regard to anything. You cannot mistake which side of the clip is the back because the front is the only side that has a hole to fit over the pin. I was surprised to find only one clip packed with the gun though. Since this is an action pistol I think you'll want at least another 3-pack of clips to keep going.

To load, flip up the top of the slide and insert an 8-shot clip.

The clips have 8 chambers with ridges running down the inside to hold the smaller steel BBs securely. Naturally, the gun will be more accurate with lead pellets, but the lighter BBs may give the highest velocity. I say may because Crosman Silver Eagle hollowpoint pellets weigh 4.8-grains and steel BBs weigh 5.1 grains. That slightly lighter weight coupled with fitting the bore tighter may allow the non-lead Silver Eagles to be the fastest. I'll certainly check that for you.

I was supposed to check something else with this gun. Several readers say the CO2 mechanism will eventually leak after several cartridges have been installed. I thought they might be over-tightening the cartridges at installation, but I promised to have a look at it for them. If I've made a mistake in this, please correct me so I can check for the right things.

Accessories
This pistol has a single Weaver notch on a rail under the slide. Accessories with Weaver rails (like flashlights and lasers) can be fitted to the gun. Unfortunately, Crosman's own laser has a 3/8" dovetail that will not fit, but there are plenty that do. There's no possibility of fitting optical sights to this pistol.

Sights
The sights are a square notch in the rear and a square ramp on the front. There are no dots or fiberoptics, which I think is the best way for pistol sights to be if you want sighting precision. The rear sight can slide left and right for adjustment. Two very small Allen screws lock it in place.

Action
The main way to shoot the pistol is double-action, but it does permit single-action operation, too. I'll try both ways for velocity and accuracy.

This pistol can be fired single-action, with the hammer back as shown here. Double-action is the preferred way to shoot, however.

Thursday, December 04, 2008

Long-term barrel storage - no grease!

by B.B. Pelletier

JP inspired this report, but so did my recent acquisition of a Russian SKS rifle. While inspecting the action of my new gun, I noted that the firing pin remained in the extended position, as though it had just been struck by the hammer. "That's not good!" I thought. "That looks like the bolt of an M3 grease gun," a .45 ACP submachine gun that was in U.S. service for 50 years or so. The M3 firing pin is fixed in the forward position so when the bolt goes forward the pin strikes the next primed cartridge. As long as the trigger is held down, the bolt keeps going forward until the magazine is empty. The only way to stop the gun firing is to release the trigger, which then catches the bolt at the back end of its cycle and prevents it from going forward.

SKS was a Warsaw Pact main battle rifle that was replaced by the AK47.

M3 "Grease Gun" is a .45 ACP submachine gun that fires from an open bolt. This is known as a "slam-fire" gun in slang terms.

An SKS firing pin is not supposed to stick out of the bolt face like this. It's should do this only when struck by the hammer. The pin has no return spring and is supposed to rebound from the primer after smacking it. If the rifle were loaded with the pin in this condition, there's a high probability that the gun would go full-auto the moment the bolt went forward the first time.

The M3 is called a "slam-fire" gun because the entire weight of the moving bolt is what drives the firing pin and causes the gun to fire. There's no separate hammer, like you'd find on a conventional firearm. Now, how does that relate to the SKS?

Well, the SKS is not a slam-fire gun. It's got a real hammer that's supposed to drive the firing pin when the bolt is closed. But if the firing pin sticks in the forward position like what I saw, nothing can stop the gun from firing. And since the trigger does not hold the bolt back, like the trigger on the M3, if an SKS starts firing full-auto, there is nothing to stop it until all 10 rounds are gone.

So this sticky firing pin was a real problem. A little research in the internet proved that, indeed, the slam-fire tendency of the SKS is its greatest flaw. The firing pin has no return spring, and if cosmoline grease or dirt gets into the bolt and jams the firing pin forward, you're in for the shock of your life.

The solution is to clean the grease out of the bolt and run it absolutely dry, but what does that have to do with airguns? Everything, if you focus on the grease. Grease has no business inside the bolt of an SKS, just as it has no business in an airgun barrel--ever!

My time capsule
Several years ago, I gave way too much money for a Feinwerkbau 124. I've owned quite a few 124s over the years, so you might wonder what was so special about this one that I gave too much for it. Just this: the gun was encased in a shrine of 1970s parts! It had been mummified by its former owner, who I must assume was also the first owner. The man had built a cabinet-grade wooden case for the rifle and put in everything the gun would ever need...period Beeman Silver Ace pellets, a replacement mainspring, three replacement piston seals (all made from the flawed 1970s formula that deteriorates with time, so they're all useless now), a sling, oils, greases, instructions and so on, until it became clear to me that this outfit was indeed a sarcophagus.

This FWB 124 was enshrined for all time by its former owner. Among the things he did that didn't work well was he plugged the barrel with grease.

And the rifle's barrel was filled with grease. By "filled" I mean that there was a solid plug of grease that ran from breech to muzzle. I know that because I pushed it out with a patched cleaning rod and saw that it was the length of the barrel. Had the grease hardened, the job would have taken much longer. Which brings me to the point of this report.

Grease does not preserve barrels! The fact that governments use a product called cosmoline to preserve metal parts should not convince you to experiment with any old grease laying around the garage. In the first place, cosmoline is a specific type of rust-preventive product. If you aren't using it, you don't have the same protection it offers. Second, cosmoline has a shelf life. I just bought some M1 Carbine parts preserved in cosmoline since the end of World War II and they were rusty! Yes, rusty. After a few decades, even cosmoline breaks down and fails to preserve metal.

Here's the funny part--real cosmoline is not grease! Yep, it's a product that resembles grease, but it isn't the same. It's really more of a wax-based compound than a grease. But that doesn't stop folks from thinking that it's grease because when it's fresh it looks like grease. Those same people think that any old grease can do what cosmoline can.

What grease can do is dry out and get hard. Then, it can crack and allow oxygen to contact the steel of a barrel...rusting it.

What to do? Leave a thin coat of oil on the exposed metal parts. That's the best protection.

"Yeah," you say, "but you have to redo that every so often because it doesn't last."

Neither does grease! It doesn't even last as long as oil.

JP: I own a 133-year-old rifle that, to my knowledge, has never had grease in the barrel for preservation. It's an 1875-version of an 1873 Springfield rifle. And the bore is fine. I keep it lightly oiled--the way the government has always insisted for their rifles.

Keep the grease out!

Wednesday, December 03, 2008

by B.B. Pelletier

Part 1 - Under \$25
Part 2 - \$50 and under

Lets get right to it. These are gifts that airgunners might like. Use the links to go to the pages where the items can be ordered.

Rifles
Beeman 1024 takedown rifle, scope and rings in case A plastic air rifle with a lot of value for plinking.
Crosman 1077 Can't do better than this!
Scoped 1077
1077 with AirSource adapter This one runs on either 88-gram AirSource cartridges or 12-gram conventional CO2 cartridges.
Crosman 2100
Scoped Crosman 2100
Crosman 2250 Another classic.
Crosman 2260 The CO2 father of the Benjamin Discovery.
Crosman 760 XLS A 760 with a wood stock.
Crosman NightStalker kit 12-shot semiautomatic. Special deal! Only a little more than the gun by itself; but it includes the gun, an 88-gram AirSource CO2 tank and 250 pellets.
Crosman Phantom 1000
Crosman Quest 1000
Crosman Storm XT scoped rifle
Daisy 22SG Get them while they last!
Daisy 880S pump with scope
Daisy 840 single-stroke with scope
Daisy 953 single-stroke The most desirable single-stroke for informal target shooting and plinking.
Gamo Delta Youth-sized breakbarrel spring-piston rifle.
Gamo Delta with scope
Gamo Recon Last year's best-selling spring-piston combo.
Hammerli 490 Best youth spring-piston rifle in this price range.
Norica Young A few remaining new-old-stock youth rifles from the 1990s.
Remington AirMaster 77 One of the most popular multi-pump rifles in this price range.
Winchester 1000B An unassuming breakbarrel spring-piston rifle that keeps soldiering on.

Pistols
Beeman 2008
Beeman 2008 with pellet trap Everything you need to shoot except safety glasses.
Beretta PX4 Storm Both BBs and pellets.
Crosman 1088
Crosman 1377 A classic multi-pump pistol!
Crosman 2240 The best CO2 pistol on the market.
Crosman C11 Tactical A tricked-out BB pistol.
Crosman C21
Crosman PRO77
Crosman T4
Crosman T4 kit Everything needed to shoot!
Daisy 008
Daisy 008 kit Everything needed to shoot.
Daisy Powerline 5501 A BB gun with blowback action.
Daisy Powerline 617X Both pellets and BBs.
Gamo P23 Both BBs and pellets.
Gamo P23 with laser Both BBs and pellets.
Gamo PT-80
Gamo PX-107
Gamo V3
SIG Sauer SP2022
Walther CP Sport
Walther CP 99 Compact Realistic BB pistol.
Walther CP 99 Compact with laser
Walther PPK/S A real value BB pistol with blowback action.
Walther PPK/S with pink grips

Airsoft guns
The following gun operates on CO2, so be sure to get some 12-gram cartridges.
Crosman Air Mag M50
The following guns operate on green gas. It appears that Pyramyd Air no longer sells green gas, so pick up a 1000ml can at Wal-Mart in the sporting goods department.
KWC Colt National Match 1911
Colt Python

Spring-piston airsoft guns
Black Eagle M6 short version A sniper rifle for under \$100!
Smith & Wesson 1911
TSD SD700 Another sniper rifle.
TSD SD700 wood stock
UTG Master Sniper This sniper rifle tested very well.

Automatic electric guns (AEG)
Crosman Pulse R72
Crosman NightProwler camo

Clear airsoft guns
Crosman R70
Crosman NightProwler
Crosman Pulse R72
Daisy Airstrike ASAX1
Walther G22 Special Operations

Other stuff
CenterPoint 3-9x40 scope
CenterPoint 4-16x40 scope
BSA pistol scope The only pistol scopes at Pyramyd Air.
BSA 3-12x50 scope
Leapers 3-9x40 mil-dot scope with illumination
Leapers 3-9x50 scope with mil-dot and illumination
Leapers 4-16x50 scope with mil-dot
Leapers 4x Bug Buster scope Focuses down to 9 feet!
Leapers Bug Buster II 6x scope
Alpha Chrony chronograph Every airgunner needs this.
Chrony chronograph printer Prints the results and provides a 16-foot separation from the chronograph. Perfect accessory for the chronograph.
AirForce LS-1 laser Fits an 11mm dovtail.
Plano double-gun scoped rifle case Every airgunner needs another big case.
Radians Maximus 29 electronic earmuffs They amplify normal sounds and stop loud impulses. Every shooter needs them but won't buy it for themselves.
Beeman DLX leather sandbags Another accessory no airgunner will buy, yet they all need these.

Tuesday, December 02, 2008

Career Infinity by Shinsung - Part 1

by B.B. Pelletier

This review has been a long time coming. I'm doing this for our rocket scientist, Jane Hansen, but several others have talked about this rifle, as well.

Career Infinity is a large precharged repeater. Powerful yet light, it should be a good hunter.

The Career Infinity is a six-shot repeater that comes in both .22 and .25 calibers. The website lists the power in .22 as a peak of 40 foot-pounds, but also lists a velocity peak of 1220 ft. sec. That doesn't quite work out, because that velocity equates to something in the over-50 foot-pound class. So one thing I will do in this series is discover what the numbers really are.

The action is a sidelever that cocks the rifle and advances the cylinder to the next pellet. It also operates the bolt probe, which feeds the pellet from a chamber of the cylinder into the breech of the barrel. This is a different arrangement than the other Korean precharged rifles I'm familiar with. No air passes through the cylinder. In fact, each chamber has a hole drilled to the outside, so air cannot be contained. Therefore, the air has to come through a transfer port in the breech. That means a couple of novel things to the shooter.

Short sidelever cocks the action, advances the cylinder and pushes the next pellet into the breech.

First, the Infinity cylinders are easy to insert in the gun. Because they don't seal air, their tolerances are much more relaxed and cylinders snap in and out quickly. Second, these cylinders are loaded from the rear. That's an important thing, because a diabolo pellet is always larger in the skirt than at the head. With other Korean rifles that use cylinders, you always worry if the skirt will fit into each chamber. I've remarked on this in tests of other guns. With the Infinity, you push the pellet in from the rear; so if it's a little out of round, it'll be squeezed down to shape as it goes. Believe me, that's much easier.

Infinity cylinders (two come with every gun) load from the rear and do not pass any air. Spring around the rear snaps into wasp waist 0f pellets, holding them in place. Pellet seater/sizer at the bottom also comes with the rifle.

Very light!
The owner's manual says the rifle weighs just 6 lbs. I weighed mine and found the Pyramyd Air specifications were closer at 6.4 lbs. My loaded rifle weighs just over 6.5 lbs. Still, that's very light for the size of the rifle. It's the same as an AirForce Condor.

Styling
You'll have to decide if the style of the rifle is for you. Shinsung has come a long way since the days of the gold bas-relief panels on their shotgun-style rifles, but the Infinity is anything but conventional. The schnabel-tipped forearm contrasts sharply with the bulbous receiver. However, the wood appears to be a form of walnut and the coarse checkering is hand-cut--something you don't see anymore.

The high comb elevates the eye of either a righthand or lefthand shooter equally well. Since there are no open sights, you need this elevation to find the scope. There's no cheekpiece, and the pistol grip is symmetrical so the stock is ambidextrous. Of course, the cocking lever remains on the right side of the receiver with no possibility for alteration, but besides that, the Infinity is usable by shooters of both persuasions. The safety is a strange gold button inside the triggerguard. It's not automatic and can be taken off and put back on at any time.

The rifle mounts easily to the shoulder, but when I hold it comfortably, the muzzle is elevated. I'll see how that affects the gun once it's scoped. The trigger blade is quite short and curled. It feels strange.

Power wheel
A power wheel under the receiver has 12 setting for variable power. Since the number of shots at full power is about one cylinder according to the testing done at Pyramyd Air, I'll be searching for the setting that gives the best combination of power and total shot count.

A manometer (air pressure gauge) located on the bottom of the forearm tells you where the reservoir stands at any time. It reads in bar, only, so 200 is the top fill level. The front fill port is covered by a Delrin cap that has an o-ring to seal out dirt. That's a good, safe design for a PCP.

Monday, December 01, 2008

The AirForce match sight set - Part 3

by B.B. Pelletier

Part 1
Part 2

Let's look at the rear aperture sight in the AirForce sight set, which is the item of greatest interest in this set. There isn’t anything like it in its price range. Let me show you.

The sight base clamps to conventional 11mm scope base dovetails. There's no scope stop, but I didn't need one when I tested the sight.

The entire sight is clamped to a vertical post on the left side. Like the front unit, this aperture has a broad range of gross vertical adjustability. And that’s before the adjustment knobs are used. It was very easy to match the height of the rear sight to the HW55 target rifle I tested it on, and it was using the rifle’s own front sight.

The rear apertuire sight adjusts up and down on a vertical stalk for gross adjustments. Production sights will have a scale on the stalk.

The click adjustments are 1/8 minute of angle, which is half the distance found on current plastic sights. Shooters will be able to move pellets around the target by hundredths of an inch. Certainly, they'll have more control over where they're sighted than is humanly possible to use, which is reassuring for a competitor.

I counted the number of clicks up and down and side to side. There were 245 clicks from one side to the other and 254 clicks from top to bottom. That works out to just over 30.5 minutes of horizontal adjustment and 31.75 minutes of vertical adjustment.

Both adjustment knobs have scales for repeat settings. The eyepiece interchanges with aftermarket accessories.

Clicks felt more than heard
The clicks are more tactile than audible and can easily be felt throughout the entire range. They never became harder or easier to adjust at any point in the test, all the way to lock at both ends of the range. The knobs were easy to turn, but stopped positively in every detent, so there's no chance of accidental movement.

Shooters will want some kind of sight movement directions on the knobs that were not on the pre-production prototype I tested. A simple arrow that indicates one direction should be sufficient for each knob.

The knobs do have index numbers around their periphery. A dot for each knob is located on the sight body to be used as the point of reference. These are the smallest adjustments that will be made after all gross adjustments have gotten the rifle in the black.

And the function?
This new sight is a positive step forward from the plastic aperture sights that come on youth models today. It has sharp, positive adjustments with no backlash or slop. I’ll show that in a moment.

Compared to the expensive target aperture sights, the AirForce sight feels less crisp. I think that's because the clicks are less audible, yet on target paper this sight is just as positive as any of the big boys. The broad range of movement gives you a sense of security, knowing that once you're in the neighborhood, you’ll never run out of adjustment.

I discovered that my Gehmann adjustable aperture fits the same hole as the removable aperture disk. And AirForce may bring out a range of apertures for shooters to adjust to different lighting conditions.

Let's test
Whether testing a scope, dot sight or an aperture like this one, there is one way to positively determine whether the click adjustments are precise or not. That is to adjust the sight in a box pattern and see where the final shots go.

I used Wayne's HW55 Tyrolean for this test. Only the rear sight was on the gun, as the barrel lacks 11mm dovetails for the front sight.

Begin by making a group at some spot on a target. It doesn’t have to be centered on the 10-ring, but that does add visual effect. Then, turn one of the adjustment knobs a specific number of clicks to the side, then up, then to the other side, then down. The last group should land exactly on top of the first group. If it does, the sight is returning to the exact same place after being adjusted away.

For my test, I centered the first three-shot group on the bullseye. While I admit that a three-shot group is not statistically sound for accuracy testing, it works for this procedure.

After the first three shots, I adjusted the sight 40 clicks to the left and fired a second group. The distance to the target was only 10 meters, and these are 1/8-minute clicks, so 40 isn’t as big a move as you might think.

Following that, I adjusted the sight 40 clicks up and fired a third group. When that was finished, I adjusted the sight 40 clicks to the right to cancel the initial 40 clicks to the left. After another three shots, the sight was adjusted 40 clicks down to cancel the 40 clicks of elevation put on the sight for the third group.

The final group of three shots were then fired. If you've followed my directions and if the sight adjusts with precision, it should be back where the test began and the last group should fall on top of the first.

First three shots in the center of the bull. Then 40 clicks left, followed by 40 clicks up, then 40 to the right and finally 40 down. The last three pellets went on top of the first three.

As you can see, my last group of three shots did fall exactly on top of the first at the center of the bull. The upper two groups are more open than the bottom two, which is due to my own shooting error, but the sight tracked the way it was supposed to. So, this sight works as advertised.

The bottom line
I've been waiting for a sight set like this for more than 30 years. Ever since the days when Air Rifle Headquarters and Beeman sold expensive target rifles without sights, starting back in the 1970s, I’ve seen too many great airguns sold sans sights. Sure, the initial buyers saved a few bucks and it was possible to use small scopes on them; but when someone wants to put one of these vintage beauties back into serious service today, they're always shocked by the \$400-\$500 cost for a new set of precision sights. Until now, the only alternative has been the inexpensive sights used on youth rifles.

Now, thanks to AirForce Airguns, you can afford to put a real target sight set on your heirloom rifle. And because this sight is budget-priced, it qualifies as a Sporter-class sight, so competitors can give their target rifles a new lease on life. Best of all, this one is made in America!