Gamo Compact target pistol: part 3

by Tom Gaylord
Writing as B.B. Pelletier

Gamo Compact
Gamo’s Compact single stroke target pistol is back.

Part 1
Part 2

This report covers:

  • The sights
  • Qiang Yuan Training pellets
  • Gamo Match pellets
  • H&N Finale Match Pistol pellets
  • RWS Hobby pellets
  • The rest of the test
  • Summary

Today is accuracy day. We get to see what the Gamo Compact target pistol can do to a target at 10 meters. Let’s get right to it.

I shot the pistol at 10 meters with the gun rested on a sandbag. Since a single stroke pneumatic has no recoil, this is the best way to check the accuracy. I know there are some who believe the gun has to be held in a vise to check accuracy, but in the European factories they test the guns hand-held.

The sights

Remember that I adjusted the width of the rear sight notch in Part 2. It turned out that I got the width just about right for my eyes, so it was very easy to hold on-target. I pulled just one shot out of 40, and I will tell you which one when we get there.

Qiang Yuan Training pellets

In the velocity test the Chinese Qiang Yuan Training pellets had the tightest velocity spread, so I started with them. You may remember back when I tested all three Chinese pellets from Qiang Yuan, that this pellet was a surprise. But that was in two different 10-meter target rifles. I mentioned in part 2 of this report that this pellet fit the Compact’s breech very loosely. So, what did that do to the accuracy?

It didn’t help — that’s for sure! Ten Qiang Yuan pellets went into as pattern (too large to call it a group) that measures 1.699-inches between centers. That’s not good at all! As good as this pellet was in the 10-meter rifles, it is not the right pellet to use in the Compact.

Gamo Compact Qiang Yuan target
Ten Qiang Yuan pellets spread out like this at 10 meters. Group measures 1.699-inches between centers.

Does that result discourage you? It would me, if I didn’t have experience with these target airguns. But the truth is, one pellet will do this and the next one will shoot tight. Let’s take a look.

Gamo Match pellets

Next I tried Gamo Match pellets. Remember I said in Part 2 that I was testing this pellet because a tin of 250 came packed with the gun. Well, they may have had the largest velocity spread, but they didn’t do so bad on the target! Ten pellets went into a group that measures 1.007-inches between centers. But look at the 7 pellets in the center! That sub-group measures 0.506-inches!

Gamo Compact Gamo Match target
Ten Gamo Match pellets went into 1.007-inches at 10 meters. Seven of them went into 0.506-inches and it appears that each of them is a score of 10 points (the second ring out from the center).

Don’t fuss about the 3 pellets that aren’t in the smaller group. Remember, I’m human and also 68 years old. Some of that dispersion is from me! I would consider shooting Gamo Match pellets in the Compact, if I were you.

I will also mention that about half of these pellets loaded very hard, and the rest were just snug. Maybe some sorting with the PelletGage would improve things.

H&N Finale Match Pistol pellets

Next I tried H&N Finale Match Pistol pellets. These loaded snugly and from my experience I expected them to do well in the Compact. I think they did. This was the pellet that I called one shot as off target. I could see when the sear broke that is was going low and to the right, and that is exactly where it went. Ten went into 0.995-inches at 10 meters — even with the shot that was called. The other 9 went into 0.726-inches. While that is larger than the sub-group of 7 Gamo Match pellets, and while I didn’t shoot as many 10s with this pellet, I would still include it in the group of pellets to be tested further.

Gamo Compact H&N Finale Match targett
Ten H&N Finale Match pellets went into 0.995-inch3s at 10 meters, but the lowest hole was a pulled shot that was called. The smaller group of 9 holes measures 0.726-inches between centers.

RWS Hobby pellets

The last pellet I tested was the 7-grain RWS Hobby pellet. That one also loaded snugly and I expected great things from it. Hobbys are pellets that often surprise me with their accuracy. But not today. Ten Hobbys went into 1.206-inches at 10 meters. The group seems to have fewer than 10 holes, but several pellets landed together. There are 10 pellets in this group.

Gamo Compact Hobby target
Ten RWS Hobbys went into 1.206-inches at 10 meters. Probably not a pellet for the Compact.

The rest of the test

So, how was the Compact in all other ways? First, I definitely would have to shape the grip to suit me. It doesn’t conform to my hand like a Morini grip would. But it also didn’t cost $250 for just the grip panels. In fact, every 10-meter pistol I have ever owned needed some work in this area.

Next, while the trigger does break cleanly now, it’s still too heavy. I am used to a 500-gram (18-oz.) release and this one goes at 1,077 grams — more than twice as heavy. That does throw me off my game.

I note for the record that the first shot of every group was a 10. But then I seemed to lose concentration to keep the rest of them there.

For plinking and informal target shooting, I think the Compact is a wonderful air pistol. It’s what you want to hold and has the accuracy to go with it. Yes, a Beeman P17 is also a delightful single stroke that is quite accurate, but it doesn’t have the grips and the sights of the Compact. You have to decide what you want.

Summary

I found the Gamo Compact to be a good value for the money. It’s in the form of a target pistol, though it’s not suited to formal competition. But for learning how to shoot a handgun, it’s a good one


Beeman R1 supertune: Part 1

by Tom Gaylord
Writing as B.B. Pelletier

Beeman R1
Beeman R1 Supermagnum air rifle.

This report covers:

  • 13-part tuning series
  • Honest talk
  • The ultimate tune
  • Malvern 2015
  • Bryan’s tune
  • Buttoning the piston
  • ARH mainspring and piston seal
  • Bronze spring guides
  • Smoother cocking arm
  • New cocking shoe
  • Stock screw escutcheons
  • Finish

Today we start looking at a rifle many of you already know. It is the Beeman R1 that was featured in my R1 book. While the R1 has changed since mine was purchased in 1994, the essence of the rifle remains the same as always. And the tuneups I’ve done over the years have pretty much obliterated what was originally in the rifle anyhow.

13-part tuning series

If you don’t know the rifle from my book, then perhaps you read about it in the 13-part report I did back in 2006. Not only did I use the rifle to show you the insides of a spring gun for the first time in this blog, I also tuned the rifle for you in that series.

Honest talk

To tell the truth, my R1 has never been the most accurate spring piston rifle I have owned. I never said it was, but I’m sure that people must think so because I wrote a book about it. In the days I was writing that book I was also discovering fundamental things about spring-gun accuracy, like the artillery hold. And I was using the rifle to test a number of theories, like how long a mainspring will last. So the rifle was as much a teaching tool and working laboratory as it was a functional pellet rifle.

The ultimate tune

In the R1 book, I documented the results of several different tunes. Some were conventional and a couple were edgy tunes that were done to prove a point more than to make the rifle a better shooter. At the end of the book I wrote that I had a dream rifle in mind that I had not yet seen. I wrote about some of the things I hoped to see in that rifle someday, but I finished the book without having seen them. That was in 1994. Today we are nearing the end of 2015, and a lot of water has passed under the bridge of my life. Twenty-one years have passed since I wrote that book and that R1 has undergone some changes, as well.

For starters, I sold it! Yes, I said I sold the rifle. I did it when times got tough for us in Maryland and I had to raise some money quickly. The man who bought it did so because he already owned my book and wanted the rifle to go with it.

Two years after I moved to Texas I was contacted by the man to see if I wanted to buy back my Whiscombe rifle. Yes, I had to sell that, as well. I did want it back, so we arranged to meet at a gun show in Maryland, where we exchanged airguns and money. He had the R1 with him when we met and I had just sold a pristine uncocked Daisy 1894 Texas Ranger commemorative in the box, so I had the money to buy it back. He didn’t like the rifle’s heavy cocking effort so we did the deal and the R1 came back to me.

He had installed a Maccari walnut stock on the rifle while he owned it. The job was done so well and the wood was so nice that I decided to leave it on, though I do still have the original stock, as well. That was the history of rifle from 2005 until now. But it didn’t sit still during that time, either.

Tom Gore of Vortek had made a gas spring for the R1 that I tested for and also for the R1 book. That unit was back in the rifle until I did a special 2-part report on the R1 18 years later. Then I tuned the rifle to cock easier and shoot slower. I got it pretty nice, but it still wasn’t what I wanted.

Beeman R1 last tune
The mainspring in my R1 was weaker, so the gun cocked easier. The spring guide was a loose fit and the mainspring is starting to cant at the far end in this picture.

Malvern 2015

I attended the Malvern airgun show this year and chanced to shoot a Beeman R10 that was lying on the table behind me. It was perfect! That was the dream tune I had been looking for all these years. When I discovered that Bryan Enoch had tuned that rifle, I made a deal with him to tune my R1. I delivered the rifle to him several weeks later and told him to take his time. I wanted the very best job he could do.

Beeman R1 Bryan's R1
Bryan holds the first R1 he tuned. This one is his own rifle. Photo provided by Bryan Enoch.

The rest of this report will be about what Bryan has done for my R1. Naturally I plan to test it for you in the conventional way.

Bryan’s tune

Before I describe what Bryan did to the rifle, let me show you the parts he made and customized. In this picture you can also see the rifle’s end cap that was trued and polished.

Beeman R1 Bryan's tune
This is what Bryan put into the R1. Notice the bronze spring guides front and rear and the buttoned piston. The stock screw cups are brass, as is the new safety bar. The face of the end cap has also been trued up and polished, so the base of the new spring guide can turn easily without friction. Photo provided by Bryan Enoch. 

The compression chamber was cleaned and honed to remove any burrs and also to freshen the cross-hatching on the cylinder walls. Then it was oiled and set aside while he worked on the other parts.

Bryan found the piston body to be oval by 0.035-inches at the base of the piston skirt. He trued it in a lathe, then he sanded and polished the piston body, even though it doesn’t need it, because it now rides on Delrin bearings (buttons) front and rear. He just wanted it to look good.

The piston rod that latches with the trigger when the rifle is cocked was found to be off-center by 0.025-inches. Bryan centered it to within 0.001-inches. He also polished it, just to make a good job of it.

Buttoning the piston

Bryan installed 3 quarter-inch Delrin buttons at the front of the piston and another 3 at the rear. They are equally spaced around the piston body to center the piston in the spring tube. He took care to size each set of buttons separately, so the piston slides easily inside the tube without being loose. This is why he wasn’t worried about trimming down the rear of the piston body to make it round. The piston body can never contact the inside of the spring tube, now that the buttons are in place.

ARH mainspring and piston seal

Bryan installed an ARH mainspring and piston seal in the rifle. He sized the seal so the piston slid inside the spring tube just the way he wanted. Both ends of the mainspring were deburred and polished so they don’t cut into the spring guides at either end.

Bronze spring guides

Bryan made custom spring guides from bronze for both ends of the mainspring. The forward spring guide is shorter and fits inside the piston. We commonly call this a top hat, because its profile looks like an old-fashiopned top hat. Not only does it prevent the mainspring from vibrating when the gun fires, it also adds some weight to the piston which makes it more resistant to bounce at the end of its travel. Each end of the guide has a Delrin washer to reduce friction.

Smoother cocking arm

Bryan also machined the cocking link arm and fitted Delrin bearings to remove any side play when the rifle is cocked. He also installed a new cocking pivot pin (where the cocking link attaches to the base block) because the old one was worn and loose. The rifle now cocks butter-smooth,  yet the barrel remains wherever I put it after the rifle has been cocked. The cocking smoothness has to be experienced first-hand to be appreciated.

New cocking shoe

When he examined the cocking shoe that connects the cocking link to the piston, he found it was cracked. He installed a new shoe on which he had first smoothed all the sides. Then he removed the piston liner to get access to the cocking slot that was milled straight and polished. When the liner was replaced it was polished so the cocking shoe rides on a slick surface.

He then cleaned the barrel (which hasn’t been cleaned in more than 10,000 shots) and installed a new Vortek breech seal. He also lightly chamfered and cleaned the transfer port.

Stock screw escutcheons

Most folks call them screw cups. Bryan calls them escutcheons. They are handmade to fit into the stock perfectly and prevent the screws from chewing into the wood.

Finish

After everything was made and fitted, Bryan lubed all the parts (with what he didn’t say), then buffed the stock with 0000 steel wool and gave it a coat of Minwax. He delivered the rifle to me at the Texas Airgun show and the occasion felt like a father giving his daughter’s hand in marriage! Bryan got his start tuning spring guns by reading the R1 book, and now he was the guy who had given her the dream tune mentioned in the book two decades later! He was keenly aware of what he had been asked to do and where it was headed.

Beeman R1 Tom's R1
I received my tuned R1 at the Texas airgun show.

How much did it cost? If you have to ask…. Seriously, though, the price depends on what you want. I wanted the smoothest tune Bryan Enoch could give me. Naturally you will hear a lot more about this air rifle in future reports.


Pneumatic arrow shooters

by Tom Gaylord
Writing as B.B. Pelletier

The history of airguns

This report covers:

  • Everything old is new again
  • Feet per second (f.p.s.)
  • FX offers many arrow launchers
  • Missing the boat
  • What I would do
  • Advantages of a pneumatic arrow launcher
  • The downside
  • Summary

Everything old is new again

This will be a different kind of history report, because today the past is also the future. Today’s topic is one that has been touched on ever-so-lightly over the years, yet is also one of incredible significance today, when hunting with airguns is at the forefront of the hobby. I’m talking about airguns that launch arrows.

I’m not talking about crossbows, though they do serve as both the inspiration and the performance baseline for this subject. The airgun that launches arrows is very similar to the crossbow, except that it exceeds it in many important ways.

Feet per second (f.p.s.)

Our cousins using crossbows are assaulted by ads that tout  f.p.s., just like we do in the airgun world. The crossbow makers are as prone to ignore the weight of the arrows or bolts their products shoot when they give those velocity figures as any airgun maker would be. The advertising appears very similar to airgun advertising, though if you dig a little you can discover the facts that really matter. This is where I will start the discussion. A hunting crossbow that shoots a heavier hunting arrow of 400 grains at 350 f.p.s. is considered a powerful hunting weapon. But you really have to dig to get the arrow weight, because the advertising is all about the velocity.

However, where conventional crossbows struggle to get velocity, airguns do not. Their struggle for airguns is to shoot the arrows slow enough

I have shot airguns that propelled their arrows so fast (in excess of 440 f.p.s.) that they were either damaging the arrows or burying them so deep in the backstop that they were damaged when extracting them. In fact, it is a little-appreciated fact that when someone shoots an arrow from an airgun that their biggest concern may be slowing the arrow down!

Swivel Machine Corp Airrow Stealth

The airgun I shot that went that fast was one made many years ago by the Swivel Machine Corporation. It was both a pellet shooter and an arrow launcher. As a pellet shooter it was a miserable failure for many reasons. It was a revolver whose cylinder had to be rotated by hand for the next shot. The tolerances were machined to the ten-thousandth of an inch, and, while that sounds good — trust me, it isn’t. The parts fit so tight that they didn’t move freely on a cold day. And the trigger was a pneumatic valve release that had to be yanked fast or all the air would leak out of the gun. That gun just wasn’t fun to shoot at all, and it wasn’t accurate — probably because of all the trigger-jerking I had to do.

But their arrow launcher, called the Airrow Stealth, worked quite well. We operated it on CO2 outdoors on a 38-degree day and I was still burying bolts so deep in the backstop that some of their hollow shafts were damaged when they were extracted. The launcher had a red dot sight and, at about 40 yards, the whole thing was very accurate. I didn’t want to stop shooting it! I didn’t chronograph that launcher, but I can believe the claim of greater than 400 f.p.s. for a heavy hunting arrow on a 60-degree day.

Airrow Stealth
I shot the Airrow Stealth on a cold day and was surprised by the performance!

One thing Swivel machine Corp saw was the potential for military sales. Arrow launchers are quieter than lower-powered pellet rifles, both because they have a lower muzzle blast and also because their arrows do not approach the sound barrier.

Swivel Machine appears to still be in business and still offers a pneumatic arrow launcher. I’m sure there have been changes in the nearly two decades since I shot one, but it still looks similar.

Another pneumatic arrow launcher of the recent past was the AirBow from Pneumatic Arms. It was pretty much the same thing — a rifle-looking launcher that shot an arrow. The trigger was a long lever grasped by the entire hand — very similar to a crossbow trigger of the Middle Ages. Not many were made and they are considered collector’s items today.

AirBow
The AirBow from Pneumatic Arms is a collectible today.

FX offers many arrow launchers

FX of Sweden has seen the light and offers several arrow launchers today. Some are made specifically for that purpose, while others are adaptations of their existing pellet guns. So, it is possible to get a new pneumatic arrow launcher, but the price is high and the wait can be long if it isn’t in stock when you order.

Missing the boat

There are also several boutique arrow launcher makers out there. They come and go with the seasons. If you want something different it pays to go online and look around, because at any point in time, somebody if probably making them.

The remainder of the mainstream airgun community, however, is missing the boat. They scramble over one another to build big bore rifles that have become the flavor of the month while disregarding the technology that has the greatest potential for bearing fruit. With hunting as hot as it is today I would think this would be the next hot thing, but it isn’t.

When I talk to these makers, they tell me that crossbows are not legal for hunting in many states today. To which I answer, “Yes, and silencers were illegal for hunting until a few years ago. Now they are experiencing a boom!” If you wait until the climate is right and all the laws have been passed, you’ll miss the boat. Get out in front of the development curve and start defining the future yourself,  rather than waiting for it to be defined for you. Everyone else will have to scramble to keep up

What I would do

From time to time over the past 20 years I have advised certain manufacturers on new airgun projects and accessories. If I were asked to do this with an arrow launcher I would advise them to build it on the chassis of an existing gun. That saves a lot of development time and simplifies production.

I would advise them to sell the arrow launcher as an upgrade to the existing platform. Even if the existing platform isn’t perfectly suited to being an arrow launcher — say the stock is too fat and heavy — make a new stock part of the upgrade.

I would advise their marketing departments to create a package that includes everything in one handy field-transportable box or case — both the airgun and the arrow launcher. Shooters like systems that have multiple applications. To put it succinctly, everyone likes MacGyver and most men own at least one Swiss Army knife.

Advantages of a pneumatic arrow launcher

I’m not against crossbows, but air-powered arrow launchers do have several advantages. Weight is a good place to begin. A crossbow gains weight as the power increases. The makers are doing a lot to keep the weight in check, but an air launcher is so much easier to trim down that there is no contest.

Bulk goes along with weight. The limbs of the crossbow stick out to the sides. Compared to them, the air launcher can be as thin as a pipe.

Cocking effort! Do I even have to say it? Cocking a crossbow is daunting — especially the powerful ones. Air, on the other hand, weighs almost nothing. And we know that the pneumatic launchers have to be scaled back to keep from shooting too fast!

The downside

I’m sorry, but I don’t see a downside to this. If you are reading this subject I assume you want to hunt with arrows, so let’s not make comparisons between the trajectory arrows and bullets.

The fact that it takes compressed air to fill the gun isn’t a drawback. You can do that with a hand pump. Hand pumps are in the same price range as electric cocking winches for conventional crossbows.

Summary

Let’s wrap this up by observing that this idea of a pneumatic arrow launcher today is as obvious as a group of chemical engineers standing around a pool of oil in Titusville, PA, in the late 1800s and wondering whether the stuff had any commercial value.


The invention of rifling: Part 2

by Tom Gaylord
Writing as B.B. Pelletier

Part 1

The history of airguns

This report covers:

  • Fine rifling
  • The Trapdoor barrel
  • Bullet deformation is bad
  • Pope’s muzzleloading breech loaders
  • Dr. Hudson
  • Airguns and rifling
  • Twist rate
  • Diabolos and twist rate
  • One last question answered
  • Summary

I am running this report immediately after the Part 1 because of the questions several readers asked. I can see that the subject of rifling is not understood that well. I stopped the first report with the invention of Ballard rifling, which I said was shallow thin lands and wide grooves. Today I will start at that point.

Fine rifling

Ballard rifling was great because of what it did — or rather what it didn’t do. Ballard rifling did not deform the bullet as much as the other kinds of rifling I mentioned last time. You will recall that I said the development of the Trapdoor Springfield rifle marked a major advance in the development of ammunition. It did not do the same for rifled barrels.

Trapdoor Springfield
The U.S. Rifle model 1873 is best known as the Trapdoor Springfield.

Trapdoor Springfield breech closed
The breech is closed.

Trapdoor Springfield breech closed
And this is where the name Trapdoor came from.

The Trapdoor barrel

The Trapdoor barrel has three lands and three grooves of equal width. That means the lands are very wide. They are also 0.005-inches high. That’s fairly shallow for a .45 caliber rifle barrel, but the width of the lands is a problem for ultimate accuracy. The lands shave a lot of lead off the bullet as it traverses the bore. That’s why when the government developed a long-range rifle on the Trapdoor platform they gave the barrel six lands and grooves. The standard twist rate of one turn in 22 inches for the 405-grain government bullet was increased to one turn in 19-5/8-inches to stabilize the heavier 500-grain bullet fired in the long-range rifle. More on twist rates in a bit.

Bullet deformation is bad

It turns out that the more a bullet is deformed by the rifling, the less accurate it will be. That was what was so revolutionary about Ballard rifling. It didn’t deform bullets as much as most of the rifling that preceded it. It was very good, but it wasn’t the absolute best.
The deformity I refer to is in the form of lead “fins” left on the base of the bullets by the lands after the bullet exits the muzzle. Harry Pope believed these fins interacted with the exiting gunpowder gasses, causing slight instabilities at the muzzle of the gun.

bullet base
You can see how the rifling lands have left lead fins on the base of the bullet at the right, after it has traversed the bore. And this bullet went through a barrel that has Ballard rifling! According the Harry Pope, this deformity causes inaccuracy because of the interplay with the powder gasses and the irregular bullet base during the first few inches after the bullet leaves the muzzle.

Pope rifling

The best rifling was made by Harry Pope. Pope put 8 extremely narrow and low lands in his barrels. He understood that the bullet base shouldn’t be deformed. And then he did something else — something that made his bullets (and barrels) the most accurate ever made, up to that time. He made his rifles load the bullets from the muzzle and the cartridges load from the breech!

Pope’s muzzleloading breech loaders

Pope believed that the base of the bullet was critical to accuracy. He knew that rifling left lead fins around the base of each bullet fired, so he made rifles that loaded from the muzzle. There were fins of lead even with his extremely narrow and low lands, but because they were loaded from the muzzle the fins were on the front of the bullet, where they didn’t affect the accuracy.

To load a Pope rifle you first loaded a dummy cartridge into the breech. This cartridge had a plug that extended 1/10-inch into the bore past the end of the case. Then you loaded the bullet from the muzzle. It stopped when it came against the plug in the dummy cartridge. Then you removed the dummy cartridge and replaced it with a loaded cartridge. The rifle was now ready to fire. Pope got such superior accuracy with his barrels and method of loading that he was backed up for many years on barrel orders.

Dr. Hudson

Around the turn of the 20th century, another fine shooter named Dr. Hudson decided to change shooting forever. He breech-loaded his bullet and pushed it into the rifling with a mechanical device called a bullet seater. The seater pushed the bullet into the bore 1/16 to 1/10-inch deeper than the cartridge would go. Dr. Hudson used bullets with rings at the back that were just slightly larger than the bore of the rifle. These bands guaranteed sealing against the gasses, and left the rest of the bullet untouched by the rifling.

bullet seater
This bullet seater just slides the bullet deep into the rifle’s chamber. This is used in a rifle whose breech block pushes the dummy cartridge into the chamber to push the bullet into the rifling.

mechanical bullet seater
This lever-type seater mechanically shoves the lead bullet into the rifling of the bore. It’s used on rifles whose breechblocks do not lever the dummy cartridge forward. That’s what this device does.

All of these special loading methods are designed to extract the absolute finest accuracy possible from a rifle. They are not for regular shooters. They are for fanatics. But they showed riflemen everywhere what the finest rifling looked like and what it could do.

Airguns and rifling

The first modern air rifle was made by the BSA company in 1905 — right at the time all these important rifling lessons were coming together. This was decades before Marlin’s Microgroove rifling had been thought of and decades before polygonal rifling was tried. But BSA was aware of one thing from the start — light lead pellets are difficult to launch with just a small puff of air. Anything that inhibits their movement — like deep rifling or wide lands, is a problem.

So from the beginning airgun rifling had low thin lands. The diabolo shape of the pellet already stabilized it in flight to some extent, so the spin from the rifling was just gravy that added more range to the pellet.

Twist rate

The twist rate determines how fast the bullet or pellet spins in flight. Longer heavier bullets need to spin faster for a given caliber. But a large caliber bullet, say .75 caliber, needs less spin to stabilize than a small caliber bullet. If you think of the planet Earth as a large ball, it spins once in approximately 24 hours and is reasonably stable.

Back when round balls were the only bullets around, the twist rate of the rifling wasn’t so important. The Hawken brothers popularized a 1:48 twist (one turn of the rifling for every 48-inches of barrel length), but that was simply because that was the only twist rate their rifling machine could rifle! It wasn’t that calculated. It happened to work, but there were rifles on the market at the same time that had 1:72 and even 1:90  twist rates. Today you’ll find shooters who think 1:48 is magical because the Hawkins used it, without knowing (or caring) why they did.

When the change was made to conical bullets the twist rate became critical. A conical bullet needs to spin on its long axis to be stable, and the twist rate has to be calculated precisely to do that. My AR-15 has a 1:8 twist rate and stabilizes 69-grain bullets perfectly. Shorter 55-grain bullets spray all over the place — the length of the bullet is that critical.

Diabolos and twist rate

But airgun pellets are projectiles with high drag. They are not entirely stabilized by spin. In fact most of their stabilization comes from the aerodynamic drag on their tails. So the rate at which the rifling spins them is far less critical.

Early airgun barrels were made by BSA and were heavily influenced by the firearms they made. They used the 1:16 twist rate of a .22 long rifle cartridge and applied it to their airgun barrels. And just like the Hawkin Brothers before them, they used the same rate of twist on all their barrels, regardless of the caliber. That practice continued with all other airgun makers, pretty much through the rest of the 20th century.

Where a .22 rimfire bullet performs differently depending on the barrel twist rate, pellets aren’t nearly as sensitive. Here is how critical it is for bullets. A .22 long rifle (shooting a 40-grain lead bullet) barrel twist rate is 1:16, but a barrel made specifically for the .22 short ( a 29-grain bullet that’s much shorter) has a twist rate of 1:20 or even 1:22. For guns that shoot both cartridges, the long rifle twist rate is used. But with diabolo pellets the twist rate isn’t as important. So for a century, 1:16 worked well.

Is 1:16 the absolute best for all pellets and all calibers? Maybe not. But not very much research has been published about what works and what doesn’t. Barrel makers probably know more than they are telling, though.

One last question answered

Reader Matt61 said this, last time.

This is great. The first question that occurs to me is one that I’ve had for awhile and may seem trivial, but it nags at me. When the bullet “catches” the rifling, does that mean that the rifling cuts into the bullet to a depth equal to the height of the land + the depth of a groove? Cutting even that much into the surface of a bullet seems like a lot.

Matt, the “height of the land” IS the depth of the groove. They are not cumulative. They are the same. Metal is cut away to form a groove and the land is the metal that remains.

How does the bullet “catch” the rifling? I asked you to tell me how it worked when the bullet was loaded from the muzzle. When the bullet is loaded from the muzzle, it is forced into the rifling by hand and pushed down the bore until it stops. The forcing is what causes the rifling (lands) to “cut” into the side of the bullet. Or, if you shoot a patched ball, the cloth patch gets jammed into the grooves, leaving the edge of the round ball untouched by the lands. When the patch spins from the rifling, it spins the ball that’s inside.

A breech-loaded bullet does encounter the rifling when it fires. Or, if you push it into the rifling during loading like I have shown here, then you are the one who pushed the bullet into the lands. In many rifles, the lands are cut on a taper ahead of the breach. This allows the bullet to be engraved gradually as it moves forward. I hope this answers your questions.

Summary

I haven’t talked about things like gain twists (where the twist rate increases as the bullets advances down the bore) and choke-bored barrels. I have discussed them in the past, as you can see in the linked report. And I will mention them again in this series.

In the next report on rifling I will concentrate on airgun barrels. I’m not going to do that as the next history report though, because not everyone is equally interested in this subject. So I’ll give it a bit of a rest. But I will come back and tell you more about airgun barrels and rifling.


Gamo Compact target pistol: part 2

by Tom Gaylord
Writing as B.B. Pelletier

Gamo Compact
Gamo’s Compact single stroke target pistol is back.

Part 1

This report covers:

  • Trigger pull
  • On to velocity
  • Gamo Match pellets
  • Qiang Yuan Training pellets
  • H&N Finale Match Pistol pellets
  • RWS Hobby pellets
  • On to the other velocity tests
  • Warming the pump head
  • Summary

Today is velocity day for the Gamo Compact target pistol, and you readers have given me several additional things you want tested. Let’s begin with a look at the trigger.

Trigger pull

I mentioned in Part 1 that the trigger on the test pistol feels heavier than mine did 19 years ago. It’s advertised to break at 3 lbs. and the one on the test pistol breaks at 3 lbs. 4 oz. out of the box. There is also some light creep (discernible movement and stopping in the second-stage pull). I told you I would see what I could do about this, so I removed the grips and looked at the trigger unit.

The Compact has a plastic cover on the right side of the grip frame over the trigger parts that are housed inside. This cover is translucent, not transparent, so you’ll need good light to see what’s happening underneath. As long as this cover remains on the gun, the gun can be cocked and the trigger will work. But pay attention to the 2 pins you see through the cover. They are axles for the trigger parts and they need the cover to hold them in place so the trigger will function. So the cover is a functional part that must be in place to use the gun.

Gamo Compact trigger cover
The trigger parts are retained in the grip frame under a translucent cover. The pins indicated are crucial to the trigger’s operation, and the cover keeps them in place. I have already removed one screw at the lower right of the cover.

Gamo Compact trigger parts
Here you see the trigger parts exposed. The part indicated by the arrow rotates up when the gun is cocked, aligning the step on its bottom with the step indicated on the other long part. The two steps with arrows pointing at them form the sear.

I put moly grease on the two mating sear steps shown in the photo. Both those parts are made from several stacked sheet metal plates rivited together, which is the same way airguns triggers were made in the 1950s. It’s inexpensive and it works well.

I did try cocking the trigger with the cover off, but the pin for the moving sear part was not held by the cover and the part started rotating out of place. So I stopped and put the cover back on. That pin tried fo fall out of the gun on the left side of the grip frame as I did this, by the way. So if you do what I did, please be careful. I don’t want to hear about parts flying everywhere!

The trigger now breaks at 2 lbs. 6 oz. — a reduction of 14 oz. from before. There is no difference in the trigger pull between dry-firing and fully pumping the gun. Best of all there is absolutely no creep in stage 2 anymore! The trigger now breaks cleanly, like a target trigger should.

On to velocity

Now let’s take a look at the pistol’s velocity. There are several things to be tested, so let’s get to it.

Gamo Match pellets

The pistol came with a tin of 250 Gamo Match pellets, so I shot them first. I found they fit the breech either very loose or vary tight and nothing in-between. Ten of them averaged 380 f.p.s. The velocity spread went from 373 to 387 f.p.s., so 14 f.p.s. That was the largest velocity spread of the 4 pellets tested.

Qiang Yuan Training pellets

Next I tried Qiang Yuan Training pellets. They averaged 379 f.p.s. with a velocity spread from 378 to 381 f.p.s. They were the most consistent pellets, with a total velocity spread of just 3 f.p.s. They also fit the Compact’s breech very loosely.

H&N Finale Match Pistol pellets

H&N Finale Match Pistol pellets were next. They averaged 383 f.p.s. in the compact and were also very consistent. The spread went from 380 to 386 f.p.s., so just 6 f.p.s. These pellets fit the Compact’s breech snugly, but not tight.

RWS Hobby pellets

The last pellets I tried were RWS Hobby pellets. At an average 386 f.p.s., they were also the fastest in the test pistol. The spread went from 380 to 391 f.p.s., so the total spread was 11 f.p.s. Hobbys also fit the breech snug but not tight.

On to the other velocity tests

Now that we know the baseline velocity of the Compact I’m testing, it’s time to look at those other questions. The first was — if you pump the gun slowly will the velocity be less than if you pump it very fast? I used the Qiang Yuan pellets for these tests since they are the most consistent.

First I shot 2 shots at the normal pumping speed — just to see where the gun was before I tested it. I got 379 and 378 f.p.s., which is exactly on spec. Then I pumped it very slowly for 2 shots. I took about 4 seconds to complete the pump stroke. I shot twice and got 379 and 376 f.p.s.

Then I pumped the gun very rapidly — taking 1/4 second to complete the pump stroke. I then recorded 379 and 381 f.p.s. It looks like there might be a subtle trend to slow down or speed up with fast and slow pumping, but it’s so close to the normal velocity that I can’t really say for sure. I would say that you can pump the Compact at whatever speed feels comfortable for you, because there isn’t a significant difference that’s based on the pumping speed. Just be sure to pump it consistently every time.

Warming the pump head

The last test I did was one that reader Siraniko asked about. I have a method of exercising the pump lever of a single stroke pneumatic to heat up the pump head by partially compressing it many times before completing a pump stroke. I call it heating, but flexing is probably a more accurate term. Heating or flexing makes the head more pliable, giving better sealing and greater velocity. I did it with the Compact and the Qiang Yuan pellets and recorded velocities of 403 and 409 f.p.s. So, this procedure does work with the Compact. And, yes, the Compact is a 400 f.p.s. gun.

Summary

From today’s tests we have lightened the trigger and made it crisper. We have also tested the average velocity with several target pellets and found the Compact to be on spec. And finally we have discovered how to get a little more velocity from the pistol, if we really need it.

The current Compact pistol seems to be very similar to the one I owned many years ago. I can’t wait to see what it can do on paper!


The advantages of hunting with an airgun

by Tom Gaylord
Writing as B.B. Pelletier

Today’s report is a guest blog about the advantages of airgun hunting by Pyramyd Air employee Derek Goins.

If you’d like to write a guest post for this blog, please email me. Now, over to you, Derek.

This report covers:

  • Introduction
  • Space
  • Noise level
  • Cost
  • Versatility
  • Some things to consider…

Introduction

Like a Carhartt-clad stone I sat motionless against a large oak tree, a rifle braced on my knees. The reluctant morning sun was just peeking into the horizon, bringing relief from the swirling fall winds biting at the back of my neck. A rain the night before left the ground soggy, the moist air heavy with the smell of earthworms and rotting leaves. Earwigs and tiny beetles fled through the humid dirt as I shifted my feet in an attempt to thaw my toes.

As a branch rustled a few feet away from me on the fence line, I looked to see a cardinal, feathers ruffled in loathing for the chilly morning. Begrudgingly he pecked and hopped about on the crisp ground for his breakfast making an awful ruckus in the dead leaves all the while.

I shifted my rifle and figured if the birds were crashing through the leaves, the squirrels were sure to be up soon. I took to scanning the pecan and oak trees that stood around me and in a few minutes a fox squirrel materialized on a leaf-barren oak branch about thirty yards in front of me. Blending right into the tree bark, the flicking of her bushy tail was the only giveaway. My hand grasped an ice cold barrel as I methodically cocked the RWS 94 air rifle in my lap.

Setting the rifle on my knee, I quickly found the squirrel in my scope. She was working on an acorn as I lined up the scope’s crosshairs. Gently sliding the safety forward I moved my finger to the trigger and nearly jerked it as the angry cardinal exploded from the ground in a huff, giving up his hunt. Seeing the elusive squirrel was as startled as I was, I settled into a steady trigger squeeze. The rifle jumped in my hands as a .22 caliber pellet snapped out of the barrel.

The squirrel tumbled out of the tree at the sound of the pellet impacting flesh. I stood up, after giving the animal a few minutes, stretching my cold limbs and walked to retrieve my squirrel. It was a clean shot behind the eye, an ethical respect any game animal deserves. The lazy morning rays finally warmed me as I stretched again and started to a large stand of pecans; relishing a good start to a dreary morning.

For many years I hunted with that airgun and not initially by choice. My family had moved to a semi-rural town in Texas and as a young man I was infected with the love of hunting. A 22 rimfire was not safe to shoot in the area and I soon discovered air rifles. The half acre property had a half dozen nut and fruit trees, to the delight of the squirrels. To this day airguns are my primary hunting arm, as there are several advantages of airguns over firearms.

Let’s begin with the very reasons most folks will get into airguns for hunting:

Space

Airguns fill a niche nicely where the 22 caliber rimfire or small bore shotgun is too much gun for the area. Simply put, airguns do not require very much space to shoot safely. The huge variety of airguns on the market right now can fit almost any space needs. The lead pellets that air rifles shoot flatten upon impact and typically do not ricochet. Additionally the moderate power levels produced by airguns let them shine over firearms for hunting or taking care of pest critters in enclosed spaces like barns or feed silos.

Air rifles like the Air Arms S510 FAC Sidelever Carbine have adjustable power, allowing the hunter a wide range of power levels for different scenarios. I have found many opportunities for hunting simply because an air rifle was a better and safer tool. Airguns have allowed me to be effective on small game from as close as 7 yards and as far as 120 yards. Under 100 yards is where the modern air rifle really earns its keep.

Noise level

With few exceptions, airguns are significantly quieter than firearms. The primary reason for this is that airgun velocities are typically sub-sonic, meaning the pellets are not breaking the sound barrier. In addition to not disturbing your neighbors, the decibel levels are low enough that the rifle report won’t cause hearing damage. Spring piston breakbarrel rifles like the Diana RWS 34 produce a dull slamming report similar to a nail gun.

For true silence, the shrouded Benjamin Marauder is so quiet that the pellet impacting the target is louder than the gunshot. The low noise levels air rifles produce will not spook animals quite as much as firearms, which is great if you want to take multiple shots. Typically a firearm rifle shot thundering through the woods will silence all the wildlife for quite a long time. It is an eerie quiet that lets you know that you’re the one who is out of place. Activity resumes much more quickly after an air rifle shot, and, though animals still react, the life in the woods remain calm. I’ve nabbed a lot of small game by bringing an air rifle on a deer hunt. More often than not I found myself putting squirrels and rabbits in the freezer in addition to venison.

Benjamin Marauder
The Benajmin Marauder is one of the quietest airguns on the market, allowing most people to shoot safely in their backyard without the ear-splitting crack of a firearm.

Cost

It’s no secret that with the turbulent firearm climate both centerfire and rimfire ammunition have had spotty availability. Long gone is the $20 brick of 500 .22 LR rounds. The same brick is over double the price now! Besides the increased cost you’d be lucky to find more than a box or two, but here I am singing to the song birds. Y’all may be nodding your heads saying, “Everybody knows that son.”

What you may not know is that you can shoot and hunt with airguns for a fraction of the cost. I shoot thousands of pellets per year hunting and stay on a trigger year-round. A tin of match-quality domed pellets may cost me $12-17 for 500, depending on the caliber — even less if I order in bulk, using the buy 3 get 1 free deal offered by Pyramyd Air. While most centerfire cartridges can be economically reloaded with the right equipment, I still can’t reload cheaper than I can shoot airguns. The cost savings is significant in an economy that’s forcing us to keep our wallets closed.

JSB pellets
JSB Exact Jumbo domed pellets are premium ammo at an affordible price.

ammunition
As much as I like shooting firearms, the drastic price increase in ammo over recent years has made shooting high quality airgun pellets the economical choice.

Versatility

Perhaps my favorite quality of airguns in general is the amazing versatility they posses. The market in the US has exploded! We’re seeing rifles capable of ethically taking down deer, coyote, fox, hog and other medium-sized animals. Rifles like the Sam Yang Dragon Claw .50 caliber can kill deer with 175 foot pounds of energy, while the Sumatra 2500 .25 caliber is ideal for coyotes with a bone-crushing 60 foot pounds of muzzle energy. These energy levels may sound low, but shot placement is the equalizer. A properly placed airgun pellet will kill an animal just as effectively as a firearm, and with less tissue damage.

pellets
Here are (from the left) .177, .20, .22, .25, .30, .357, .45 and .50 caliber pellets. The huge variety of airgun calibers now on the market allow not only small game hunting but medium and large game as well!

Some things to consider…

While I view the airgun as the ultimate hunting tool, there are a few things you’ll want to consider before making the jump yourself. The first thing I would do is check hunting legislation in your state or county. In many states airguns are not yet legal for hunting small game. Other states have caliber restrictions without regard to actual muzzle energy. To confuse things further some states consider certain animals to be game animals while others are not. For example, when I last lived in Texas, squirrels were considered game animals and thus not legal for airguns, however cottontails you could take year-round.

The power and low noise is great but it does come at the cost of reduced range. Airguns have similar ranges to archery, and you will simply need to keep this in perspective for your skill level. The challenges that come with stalking animals in airgun ranges can be quite rewarding. Most of my shots on animals are under 50 yards. While longer shots can be taken, you’ll want a well-tuned rifle and some experience with it before considering those.

I know that airguns will never fully replace firearms, but they do make a fantastic alternative when the situation dictates. As always, take my word with a grain of salt and do a bit of research. You may find that you have an open space in your gun safe for a well-built air rifle!

Semper Fi,

Derek Goins


POI shift when changing the scope’s power

by Tom Gaylord
Writing as B.B. Pelletier

Part 1
Part 2
Part 3

This report covers:

  • The last test
  • TX200
  • First group at 14X
  • Second group at 6X
  • Third group at 14 X
  • The final group at 6X
  • Conclusions
  • Summary

This report is an unprecedented final look at how the point of impact (POI) changes when the power of a variable-power scope is changed. I linked to the 3 earlier reports in which this phenomenon was tested (it wasn’t tested in the first report of the Aeon scope, but I included it for continuity). The scope used in today’s report is different, so we will see whether that makes a difference to the results.

I had no intention of conducting this test, but then reader Silver Eagle asked this:

Can we try this same test with a airgun that does not have the variable pressure that a PCP has?
An accurate springer such as a TX200 or similar would help narrow it down if it is the scope or the rifle.

The last test

I had thought about that when I conducted the last test and noticed that my groups were larger and smaller depending on the air pressure in the gun when I started shooting. I mentioned that in the report, and Silver Eagle caught it. So what he asked was the same thing I also wondered — if there was no change that resulted from the gun, what would the groups do when the scope’s magnification was changed? Granted I’m using a different variable scope for today’s test, but if this phenomenon is common to all variables, we should still see it.

TX200 Mark III Tom bench
This time I shot my TX200 Mark III.

This will be the last time I conduct this test. It’s not that I have proven or disproven anything conclusively. In fact, just the opposite. I have opened a can of worms and they are scattering everywhere! There are so many variables here that I don’t have enough time left on earth to test them all. But I wanted to see what kind of results I got from a different kind of airgun and a different scope under similar test conditions.

TX200

Silver Eagle suggested the test. Why not shoot my TX200 Mark III at 50 yards and see whether changing the power on its variable scope changes the POI? The rifle is currently scoped with the 4.5-14X42 Sidewinder Tactical scope that I have found to be one of the finest riflescopes I have ever used. While it doesn’t have the magnification of the Aeon 8-32 AO scope with trajectory reticle that I tested before, this scope is astonishingly clear. It should be able to perform this test at 50 yards on much lower power.

I chose to shoot at 6 power and at 14 power. That should be enough separation to show a POI change if there is going to be one. For my pellet I selected the Crosman Premier 7.9-grain dome because this rifle likes it a lot. When I first shot the rifle on this day, the impact point of this pellet was about 2 inches low. An adjustment raised the POI into the bullseye. The rifle was fired with the stock rested directly on a sandbag, as that has proven to be the most accurate way to test this airgun.

First group at 14X

The first official group was fired with the scope set at 14 power. The wind was dead calm throughout the test, so conditions were ideal. On this first scope setting, 10 pellets went into 1.519-inches at 50 yards. The group is centered on the bull and is fairly round. This will be our baseline.

TX200 Mark III Premiers 14X
Ten 7.9-grain Crosman Premier pellets landed in 1.519-inches at 50 yards when the scope was set on 14 power.

Second group at 6X

Next I adjusted the scope back to 6 power. The parallax appeared perfect, but at 6 power it’s impossible to know for certain at 50 yards. I shot another 10-shot group. These pellets went into 1.073-inches. The group is still well-centered, but the center of the group did drop by about 1/8-inch. That’s definite movement, but not enough to be concerned about.

TX200 Mark III Premiers 6X
Ten 7.9-grain Crosman Premier pellets landed in 1.073-inches at 50 yards when the scope was set on 6 power. The center of this group is in the same place left and right, but about 1/8-inch lower than the last group.

We learn two important things from this second group. First, there is a slight but definite shift in the center of the group. It’s not large, but it’s there. That addresses the question of whether the POI shifts when the magnification is changed. We have now seen it on all three of my tests with a pellet rifle at 50 yards, plus I told you about a much larger shift at 200 yards that my buddy Otho experienced.

The second thing we see is that the rifle grouped better with the scope set on lower power than when it was set on high. If you recall, I did a test of that phenomenon for you in response to the question posed by our Moscow correspondent, duskwight. Duskwight also showed that in his guest blog that was in response to the test I conducted a week earlier.

I don’t think the scope’s magnification has much to do with the group size. What I think is that as long as the image in the scope is clear you can do just as well with it set on low power as when it is set on high. And that’s exactly what I did next.

Third group at 14X

For the third group I adjusted the scope back to 14X. That should tell us two things. First, does the group shift back to where it was initially with the scope set at 14X, and second, is this group larger or smaller than the one shot on 6X?

This time 10 pellets went into a group measuring 0.916-inches between centers at 50 yards. So this group is a little smaller than the last group that was shot at 6X. But notice that the POI shifted back up again. Perhaps it isn’t in exactly the same place as the center of the first group, but it’s easy to see that it is higher than the group shot at 6X.

TX200 Mark III Premiers 14X 2
Ten 7.9-grain Crosman Premier pellets landed in 0.916-inches at 50 yards when the scope was set on 14 power. The center of this group went back up to almost where it was the first time I shot at 14X.

The final group at 6X

Now I adjusted the scope back to 6X to shoot the final group. Will the center of the group drop back down again?

This time 10 pellets went into 1.295-inches. And the center of the group definitely dropped below the enter of the last group. It’s even a little below that last group shot on 6X.

TX200 Mark III Premiers 6X 2
Ten 7.9-grain Crosman Premier pellets landed in 1.295-inches at 50 yards when the scope was set on 6 power. The center of this group dropped even lower than where it had been at 6X the first time.

Conclusions

There are several conclusions we can draw from today’s results. First, there seems to be no question that the POI does shift when a variable power scope’s power is changed. I believe this differs from scope to scope. Some scopes will shift more than others. I recommend that you test your variable scopes this way on every airgun you own and see what results you get.

Next, I think this test demonstrates once more that the power of the scope has very little to do with how accurately you can shoot with it. While I was conducting this test I was also testing a Remington 788 30-30 rifle at 200 yards. I have a Leupold M8 4-power scope on that rifle, yet I was able to see the crosshairs against the black bullseye clearly at that distance. Optical clarity is the most important thing in a scope, I think.

TX200 Mark III 30-30 200 yards
Six 30-30 bullets went into 4.559-inches at 200 yards when fired from a Remington 788 that was scoped with a 4-power scope. Any one of these is a kill shot on a deer at that range.

Finally I was surprised to see my TX200 Mark III do better at 50 yards than my Talon SS. That Talon SS has long been my go-to air rifle when the ultimate in accuracy is required. This test taught me that the TX is another solid performer. I’m not saying the TX is more accurate than the Talon SS, because I don’t think it is. But for today’s test it was the ideal gun to use.

Summary

As I said at the start of this report, this is the last test I will do specifically on this question. Of course I will remember these results in all my future shooting, as I hope you will. This lesson is too hard-won to forget. Test your scopes under the conditions you intend using them, and remember their results. That should make you a more confident shooter, and confidence builds skill.