Posts Tagged ‘testing’

The great accuracy test: Part 1

by B.B. Pelletier

I am on the road with Mac today. I will be back on Wednesday, so I’m asking all the old hands to help the new readers with their questions.

Today, I have a huge audience participation test starting up. We’re all going to design a test to prove what are the most beneficial things you can do for accuracy and what doesn’t matter. I envision this as a series of tests to demonstrate what really works and what doesn’t matter.

Before we can do even that, we all have to decide what accuracy is. I’m writing an article for this website and I’m struggling to define accuracy, so this isn’t as straightforward as it seems. One guy measures 50-yard groups with a caliper and another drops field targets. And a third guy is looking for how fast the squirrels fall from the first shot. Yet they all use the same word –accuracy — to describe what’s important to them.

So, what does accuracy really mean? How will we know it if we see it? Remember, somebody, most likely me, will have to actually do this test, so let’s keep it real, okay? This is where you guys with your guns in vises have to be reasonable, because nobody takes a vise to a field target match or into the woods.

Many will say they want to know how accurate the rifle or pistol is, so if they’re off they know for sure that it’s them and not the gun. Please, don’t be so naive! The gun can always be a source of inaccuracy, regardless of how accurate you think it is. So, we have to keep this discussion out in the open and in the real world where we can really conduct a test and believe the results.

To give you an idea of what I mean, let me take a stab at it.

Testing for accuracy
I think the first thing is to select a certain airgun. Then that gun should be tested under realistic conditions and circumstances. That means no 100-yard shooting, and no shooting inside a warehouse where there is no wind. We need to use a realistic range (meaning distance to the target) and a realistic shooting position. I like shooting from a bench, because I can do my best there. And I like shooting at least 25 yards, because it’s easy for me to get that much range (meaning more tests can be conducted), which gives me a greater body of data to examine.

Once a baseline of testing is completed, experimentation may begin. For example, given the most accurate rifle and pellet from the first test, how much improvement can be obtained?

Does sorting the pellets by weight make much difference? How about sorting by size? How would we do the latter?

Are there any other things we should do regarding pellets?

How much of a factor is wind? Should we ignore it, or try to cancel it altogether?

The gun can always be a source of inaccuracy, regardless of how accurate you think it is.

Some concerns
If we use an expensive rifle as our testbed, very few readers will be able to participate. I want this to be a test that almost anyone can enjoy.

If we start out with the most accurate airgun we own, there might not be much room for improvement. Here’s what I mean by that. Two weeks ago, when I showed a group I got with a 10-meter rifle that measured 0.16 inches and compared it to a group measuring 0.24 inches, a couple readers thought that it didn’t look very different. And, we have readers who are convinced that there are rifles that can put five pellets under 0.08 inches repeatedly. A 100 percent improvement over a group of that size would not look very dramatic.

If, on the other hand, I selected a rifle that groups 5 shots into 2.0 inches at 25 yards, it may not be capable of grouping much better. It would then be nothing but a waste of time. I need to pick something that’s reasonably accurate, though not the most accurate rifle known.

The rifle I select should be common enough that any reader should be able to pick something equivalent, even if it isn’t made by the same manufacturer. So, I might choose a Diana 34, but you might do the same test as me but maybe with a Gamo Big Cat. In my rifle, a certain JSB pellet might be the best, while in yours it might be a particular RWS pellet. Understand? I was tempted to choose a TX200 at first, but that isn’t good because there aren’t a lot of rifles that can match it and they would all cost a lot of money. I could choose a Marauder and the same reasoning applies. But a Diana 34 is a plain old breakbarrel that exists in enough quantity that most readers would have a decent chance to run the test right alongside me.

If we do it that way, you can choose whatever model rifle you want and use a different pellet than I do. In fact, I don’t see why you couldn’t choose a different powerplant altogether if we do it this way. However, once you establish your baseline, you have to stick with it throughout the test, or the results become meaningless.

I think 10-shot groups are right for this test, rather than 5. Ten shots are far less capricious than 5. The best groups will tend to be close to the same size. Until we have that, we shouldn’t proceed, because we haven’t found the real baseline yet. Once we get a couple groups of the same size and they’re better than any other pellet/hold/anything else, we have our baseline.

I’m going to use a good scope for this test, because my eyes are not what they used to be. Yes, I can shoot tight groups at 100 yards with the Ballard, but no sporting airgun sights are as good as the ones on the Ballard. A 10-meter rifle has sights just as good, but a 10-meter rifle is at a disadvantage shooting at 25 yards, plus not as many people will be able to participate.

My vision for this test
Here’s what I see happening. In the first test phase, we’ll establish a baseline for accuracy with the test rifle. Hopefully, we’ll find a really accurate pellet and shoot a couple groups that are similar in size. I plan on selecting domed pellets for the baseline test, because in all of my experience, they’ll out-shoot any other pellet shape at 25 yards.

Then, we’ll begin testing things that supposedly improve accuracy. Some of these may be:

  • Sorting the selected pellets by weight.
  • Sorting pellets by size (if we can agree how that’s done).
  • Cleaning the barrel.
  • Lubed pellets versus dry pellets.
  • And anything else we can agree to test. If you want me to test something, you have to submit a test plan and the reasoning why you think it will work. Just dreaming up things doesn’t cut it; but if you’ve done this and think it works, that might fly.

    The expected outcome
    I hope to show the things that work and the things that don’t. When anyone wants to improve their accuracy in the future, they can take the recommendations we get and apply them to their own situation.

    Will it work?
    I have no idea. Right now, I do think there will be a difference in group sizes between weighed and random pellets. Back when I competed in field target, I did weigh all my pellets. Because I shot a PCP at the end of my competitive years, I also lubed all pellets. I believe that does help, too, if the rifle is a PCP, but I want your input into this. In other words, what have I forgotten?

    Please give me solid recommendations that I can act upon, and I’ll assemble them for the first test. At this point, everything is open to interpretation and debate, so please let your voice be heard!

    A shrine built for a Feinwerkbau 124 – Part 15

    by B.B. Pelletier

    Part 14
    Part 13
    Part 12
    Part 11
    Part 10
    Part 9
    Part 8
    Part 7
    Part 6
    Part 5
    Part 4
    Part 3
    Part 2
    Part 1

    Welcome to the longest blog segment I’ve ever written. This is part 15, and I’m not going to guess whether there will ever be another. This blog began as my report on a 124 I got years ago that had been preserved for the ages. After going through several tunes on that rifle, I explored the foundations of the Beeman company and the three addresses of Robert Beeman’s store. That ties into my mummified FWB 124 because it has a very rare and very early San Anselmo address.

    Then, I went to Roanoke and returned with journalist Mark Taylor’s 124 that I promised to tune for him. That became Part 13 of the report. While registering a Sheridan Knocabout pistol at my local gun dealer’s. I stumbled across another FWB 124 that I showed you and tuned for you in part 14. You got to see what an original 124 piston seal looks like when it disintegrates and I tuned the rifle with a Maccari kit for you. Well, today I’ll show you the accuracy of that rifle. But first, just to remind you of what it looks like, how about a picture?

    This is the FWB 124 Sport I acquired at the gun store while registering another firearm. I’ve tuned it for you, and today we’ll see how accurate it is.

    Look at the scope
    The first thing I want you to do is take a look at the scope that came on the rifle. That’s not an airgun scope. It’s a 4x .22 rimfire scope that holds onto the rifle’s dovetail grooves by clamping pressure alone. Usually, that won’t work unless you have BKL scope mounts that are made for it, but this little scope is so lightweight that it holds tight. The scope also slides on the top side of the clamp, so it’s double-adjustable for eye relief.

    This is not an air rifle scope. It’s a cheap .22 rimfire scope, and the parallax is way off. The scope slides along the rail that clamps it to the rifle. Even with this scope, however, the 124 was accurate.

    But it’s not a quality optic! It has no parallax adjustment. The way the scope is designed, I didn’t see an easy way of adjusting it with the objective lens. So, at the 25-yard range I shot, the bulls were fuzzy — to say the least.

    All shooting was done on an indoor range at 25 yards off a rest. Because this is a 124, you need quite a bit of technique to shoot accurately. By that, I mean the artillery hold. I slid the rifle forward on the palm of my off-hand until the heel of my hand touched the triggerguard. That way, the rifle is muzzle-heavy, which produces the best groups.

    I also broke with my tradition of 10-shot groups because I wanted to test many pellets. This time, I shot the 5-shot groups we’re all familiar with. Obviously, 10-shot groups would be larger than the ones you’ll see.

    Air Arms Falcon pellets
    The Air Arms Falcon pellet weighs just 7.33 grains and is a preferred (for longer-range accuracy) domed pellet. They’re tricky in wind. If the air is still, they perform well at the power level of this 124. They have good potential in this rifle, but perhaps not the best, as we shall soon see.

    The lightweight Air Arms Falcon pellet grouped 5-shots okay at 25 yards. Group measures 0.626 inches across.

    JSB Exact 8.4-grain pellets
    Next, I tried the JSB Exact 8.4-grain domed pellets. Being heavier, I thought they might group tighter than the Falcons, and they did. Barely.

    Five JSB Exact domes were also good at 25 yards with the 124. They measured 0.612 inches across.

    Beeman Kodiak pellets
    The Beeman Kodiaks proved downright disappointing. Usually Kodiaks do well in a 124, but this rifle wasn’t having any of it.

    Five Beeman Kodiaks made this disappointing pattern at 25 yards. It measures 0.781 inches across.

    Crosman Premier 7.9-grain domes
    Following the Kodiak disaster, I tried Crosman Premier 7.9-grain “lites.” I figured they’d perform better in this rifle, but please remember that I was fighting the poor optics of the scope. The vertical string, though tight, tells me Premier lites are not right for this rifle.

    A vertical string tells me the Premier lite isn’t the best in this 124. Although it measures 0.594 inches, the vertical stringing is cause for concern. The stock screws were all tight.

    JSB RS domes
    While they have performed well in other rifles, in this 124, JSB RS domes were only mediocre in this rifle. You may think they’re the same as the Falcons, but the groups prove different.

    Five JSB RS domes went into this 0.763-inch group at 25 yards.

    Air Arms 8.4-grain Field pellet
    And then I hit it. The best pellet! The Air Arms 8.4-grain Field pellet shot amazingly tight, even with the optical problems.

    Five Air Arms 8.4-grain domes went into this tight group that measures 0.385 inches.

    So, this FWB 124 is accurate, just like all of the others. Now, it has a long-life tune that’ll keep it that way for many years and thousands of shots. If the scope is replaced, we might expect to see these groups shrink even smaller.

    I no longer own the rifle. I traded it for another FWB target rifle that needed an overhaul. While I can do a 124 with ease, I do not trust myself to do the same thing on a recoilless target rifle, so I sent off my vintage 150 for someone competent to do the job. When it returns, I’ll test it for you some day in the future.

    One of our blog readers got the 124, and it was ready to start shooting the minute it came out of the box. If he cares to, I would welcome his report as the new owner of this classic sporter.

    A shrine built for a Feinwerkbau 124 – Part 14

    by B.B. Pelletier

    Part 13
    Part 12
    Part 11
    Part 10
    Part 9
    Part 8
    Part 7
    Part 6
    Part 5
    Part 4
    Part 3
    Part 2
    Part 1

    Airgun Academy videos #19 and #20 are now available.

    2011 airgun show calendar
    Before I get to the report, here’s a calendar of all the 2011 airgun shows I know of. If you want to go to an airgun show, here they are.

    March 5 & 6
    Pacific Airgun Expo
    Placer County Fairgrounds
    Roseville, CA
    Contact Jon Brooks @ 707-498-8714

    April 9
    Flag City Toys That Shoot
    Lighthouse Banquet Facility
    10055 S.R. 224 West
    Findlay, OH 45840
    Duane Shaferly @ 419-435-7909
    Dave Barchent @ 419-423-0070
    Dan Lerma @ 419-422-9121
    To register contact:

    April 15 & 16
    2nd Arkansas Airgun Extravaganza
    Fairgrounds, Exit 98A on I-30
    1605 Martin Luther King Blvd.
    Malvern, AR 72104
    Contact Seth Rowland

    June 11 & 12
    5th CT Airguns Airgun Show
    Windsor Elk Lodge
    Windsor, CT
    Contact Kevin Hull @ 860-649-7599

    July 15 & 16
    Airgun Show and Shoot
    American Legion Post 113
    Baldwinsville, NY
    Contact Larry Behling @ 315-695-7133

    August 21
    Daisy Get Together
    Kalamazoo County Fairgrounds Expo Center
    Kalamazoo, MI
    Wes Powers @ 517-423-4148
    Bill Duimstra @ 616-738-2425

    September 17
    St. Louis Airgun Show
    Stratford Inn Garden Room
    800 S. Hwy. Dr.
    Fenton, MO 63026
    Contact Gary Anthony @ 636-861-1103

    This is the 14th report I have made on the FWB 124. In all that time, I was mostly tracking a single 124 — the one I obtained that had been packed for eternity in a wooden case like an Egyptian sarcophagus. We went through many tunes with that gun and saw what each one did. Then, I tuned a 124 for Mark Taylor, a shooter I met at Roanoke. That one wasn’t planned, but it did give us a look at a later and different rifle.

    Today, I’m reporting on the bluebird buy I happened upon while registering a firearm several weeks ago. The guy at the gun store owned this 124 that had suddenly stopped shooting, a fault that is common with this model because of a bad formula of synthetic used in the piston seal. You’ll also see it in FWB 150 and 300 rifles, Walther LGV air rifles and probably a lot of other airguns made back in the 1970s. The fix is to install a new seal. You’ve already seen me do this several times in this series, but the one thing I haven’t shown you is what the old seal looks like when it’s broken up inside the gun, and that’s something all airgunners should know.

    I originally thought I was going to tune this for the guy at the store, but he wound up selling me the rifle, so I’ll do both a velocity test after the tune and an accuracy test using the curious little Bushnell scope that came on it.

    How the new gun differs from the old
    Before I tear into the action, let me report on how this later 124 differs from the ones I have already shown you. The Deluxe models weren’t made when this one was built. It’s called a Sport, but it has a checkered grip and sling swivels, two features from the older Deluxe class. Gone, however, is the Wundhammer palm swell, and the cheekpiece that’s on the left of the butt of this later rifle is so small and ill-formed as to make the rifle nearly ambidextrous. With the ambi-style safety and the ease of breakbarrel loading, it should have been an ambi from the start.

    When I tore into the gun, I initially wondered if it had ever been apart. The serial number is 42,648, which places the gun very late in the production cycle. So, it could have been a virgin rifle, but it wasn’t. The mainspring was coated with moly grease, a sure sign that someone has been inside, because the factory used only clear grease. From the look of the tune — moly on the mainspring, an FWB mainspring instead of an aftermarket spring, a replacement FWB piston seal (a Beeman trademark, even though they knew about the disintegration problem) and the trigger adjusted very nice — I believe this rifle was last tuned by Beeman. All those characteristics are the ones Beeman would do. As good as they were, even Beeman could not prevent that piston seal from decomposing. And, that’s what I want to show you.

    This is what a decomposing FWB seal looks like. The brown particles you see used to be hard, tough synthetic. Now, they’re soft, waxy particles that break apart easily.

    In this view, you see hundreds of smaller particles in the tube; and at the bottom (the end farthest from you in this picture), the top of the piston seal has broken off and wedged itself against the end of the compression chamber. The small hole at the lower right inside the compression chamber is the air transfer port. All of this mess must be removed before the rifle can be tuned.

    There isn’t much left of the piston seal after it disintegrates. Most has been left inside the compression chamber, but this root has to be cut out of the piston top. Like most of them, this one popped out easily.

    I won’t say anymore about disassembly and reassembly except for one thing. Installing the bolt that holds the trigger assembly in the gun is a tricky job. The trigger assembly has the spring guide and is what keeps the whole powerplant together. The bolt is hardened steel, but the trigger housing into which it threads is softer aluminum. You can easily cross-thread the bolt if you aren’t careful. If you do, the trick is to remove the trigger housing from the gun and carefully thread the bolt into the hole, keeping the head aligned straight. It’ll reset the threads in most cases and you’re home free. You can then assemble the gun, and the bolt will not cross-thread anymore. This is the biggest reason you need a mainspring compressor to do this job.

    This large bolt with the two flats for gripping is what holds the 124′s powerplant together. It threads into the soft aluminum trigger housing and can easily be cross-threaded. This photo shows an older 124 trigger assembly, not the one from the newer gun I’m testing in this report…which has an aluminum trigger blade.

    Many tunes — final satisfaction
    I tried several combinations of springs and piston seals until I settled on the Maccari Mongoose spring and seal. At first, the seal was way too tight, as it’s supposed to be, so I sized it by hand-sanding until it had just a little resistance in the compression tube. The spring was lightly lubed with moly grease, and the seal also got a coat of moly before going back into the gun.

    Crosman Premier 7.9 lites
    The first pellet I tried with the new tune was the Crosman Premier 7.9-grain “lites.” They’ll be among the most accurate in this rifle; history has proven many times. They averaged 761 f.p.s., with a spread from 752 to 770 f.p.s. The average velocity produced a muzzle energy of 10.13 foot-pounds. All pellets were tight in the breech

    RWS Hobbys
    Next, I tried RWS Hobbys, a 7-grain pellet that’s the speed-demon of the lead pellet world. They averaged 821 f.p.s., but a curious thing was happening as I shot them. The velocity kept increasing! Shot one went just 767 f.p.s., but the fastest shot among the 10 I fired went 832 f.p.s. With the average working out to 821, you can see that velocity was climbing all the time. I think this tune will wear in to the point that the Premiers will go about 800 f.p.s., and the Hobbys will get up to 860 or so. At the average velocity, the muzzle energy was 10.48 foot-pounds.

    Beeman Silver Jets
    The last pellet I tested was the vintage Beeman Silver Jets that are no longer available. They were the No. 1 go-to pellet when the 124 was in its heyday. Back in Part 10 of this report, I tested them against the best of today’s pellets, with the result that they weren’t far from the leaders.

    The 8-grain Silver Jets averaged 732 f.p.s., with a range from 721 to 747 f.p.s. At the average velocity, they were generating 9.52 foot-pounds.

    I mentioned that this rifle has a nice trigger. It’s sort of a single-stage, by which I mean that pressure is there immediately when you begin the pull, and there’s no obvious hesitation. It breaks with only 26 oz. of pressure, and it feels like less than a pound. I have to be very careful, because I’m used to three-to-five-pound triggers on the rifles I shoot the most. This one feels like nothing to me.

    Most 124 triggers have more creep in them than this one. When I owned Mrs. Beeman’s personal custom 124, the Queen Bee rifle, I found that the Beeman company could really adjust a 124 trigger very finely. Whenever I feel a good one, I always suspect someone from Beeman has been inside.

    Well, that’s it for this test. Next time, I’ll see about sighting-in the rifle with that unusual scope.

    Why do you need a chronograph?

    by B.B. Pelletier

    Okay, the bottom line is, you don’t need a chronograph. If all you do is shoot, you never need to use a chronograph for anything. But, if you want to get the optimum performance from your airgun and if you want to diagnose the health of your airgun, a chronograph is an essential piece of equipment.

    Imagine a doctor without a stethoscope. He’s still a doctor and he can still do lots of things; but a major tool has been taken away, and there’s no way he can get around not having it. That’s you without a chronograph. Allow me to explain.

    Let’s say that you want to get into the world of precharged airguns, and let’s say you’ve read enough to understand that you don’t just fill them to their maximum fill pressure and start shooting. Oh, you can do that, and it’ll work, but you’ll never know how well it works unless you can diagnose how the gun performs. Let me illustrate with a story.

    Years ago, I bought an Air Arms Shamal precharged rifle for a great price. It was a beautiful rifle in .22 caliber and I was anxious to get started, so I filled it to 3,000 psi and began shooting. Fortunately, I owned a chronograph that I was using to test the gun. The first shots were in the low 500 f.p.s. range, when I had expected .22-caliber Crosman Premiers to go at least 800 f.p.s. I kept right on shooting that rifle, and after about 60 shots it finally climbed up to the 800 f.p.s. level. Because of the chronograph, I discovered that the maximum fill for that rifle was only 2,600 psi. I still got about 40 powerful shots, but they happened at a different range on the pressure scale.

    Years later when I the technical director at AirForce Airguns, I used to get calls from new Condor owners who were having problems with their guns. They were shooting very slowly when filled to 3,000 psi. I convinced some of these people to try lower maximum fill pressures until the first shots were powerful, but this could all have been solved if they had simply used their chronographs to determine the same thing. Sometimes, the disparity was due to pressure gauges that weren’t in agreement, but other times the rifles themselves were simply not performing well at 3,000 psi. Drop them back to 2,800 or 2,700 psi, and they work fine and still get just as many shots that were just as powerful as every other Condor.

    I actually had several people tell me that because AirForce was a manufacturer they should control the maximum fill pressure of their guns better than that. I countered with the fact that they were losing nothing by their guns operating at a lower pressure level, but they weren’t satisfied. They said the company advertised a fill pressure of 3,000 psi and that is what it should be. Since I helped build and test those guns, I knew they operated in a range of fill pressures depending on dozens of variables, but that wasn’t good enough for these guys.

    A correlation would be someone who buys a new car and then gets mad because it won’t go as fast as the speedometer indicates at the top end. Almost every car is like that, but nobody ever goes that fast, so nobody notices.

    Then there are the folks who think that if a multi-pump is powerful on just 10 pumps, it should crack like a .22 on 20. You absolutely cannot convince them that their guns are shooting slower when they exceed the maximum number of pumps — just like a Corvette goes no faster if you try to put an extra 30 gallons of gas in the tank. In this situation, a chronograph is a de-liar. Just like a fish scale or a ruler, a chronograph tells the story the way it really is instead of what your dreams project.

    A chronograph can also tell you when that old multi-pump no longer performs to spec like it once did. Maybe the pump head needs to be adjusted or maybe it just needs to be oiled — the chronograph tells that story.

    A chronograph can instantly tell you the health of your single-stroke pneumatic. In fact, it’s the only way we have of knowing what the health really is. I use a chronograph when I oil the gun to see the before and after comparison.

    …a chronograph is a de-liar. Just like a fish scale or a ruler, a chronograph tells the story the way it really is

    CO2 guns
    Oh, yeah, that new shoot-em-upski is a real powerhouse at 490 f.p.s. But, when you pull the trigger as fast as you can, shot 5 comes out the spout at 376 f.p.s. The only way you will every know that is with a chronograph. Or, how many shots do you get with a fresh CO2 cartridge? Or, how does the cold weather affect velocity? Or, how does that new tuned valve compare with what the factory sent? And any of a dozen other interesting vital statistics about your gas gun are waiting inside your chronograph.

    Spring guns
    How can you own a springer and not have a chronograph? Sure, the manufacturer says it shoots 1,000 f.p.s., but you really want to know what it does when shooting that one best pellet — the one that hits what you shoot at. Finding out you are shooting 789 f.p.s. with your best pellet allows you to make all sorts of adjustments to taylor the performance of the rifle to the real world.

    Or, what happens when you oil the gun? Only the chronograph will tell you the truth.

    How will you know when you have broken a mainspring? Diana rifles just get smoother and lighter to cock when their springs break. Unless you know the velocity, you’ll never have a clue what the gun’s doing.

    What about that tuneup you just did? What did it do for you? Without a chronograph, you’re just relying on your senses, and they can fool you every time. Let me tell you another story.

    Back when I was testing the Beeman R1 for my R1 Homebrew series in The Airgun Letter, which turned out to be the foundation of my R1 book, I chanced to install a Venom Mag 80 Laza Glide kit. The cocking effort jumped up to 50 lbs., but when the rifle fired it was so smooth and quiet you would have sworn it was only producing 15 foot-pounds of energy. It took a chronograph to prove that it was actually up to 23 foot-pounds.

    Sure, you can shoot into boards and duct seal and all kinds of other mediums, and you’ll get relative comparisons. To put an absolute number on those speeding pellets, you need a chronograph.

    They’re not expensive
    Yes, I know, spending $100 for something that isn’t an actual airgun is hard to do. It’s hard for me, too. I also know there are those who are living at the edge of their finances and just cannot afford anything beyond that next tin of pellets. So, I’m not talking to them right now. But for the rest of you who, over the course of a year, spend $300 and more on your airgunning hobby, you do have the resources to own a chronograph. You just don’t have your priorities aligned correctly, because you don’t see the need. That’s what today’s report is all about…to show you the need to own the most helpful piece of equipment you can imagine for airgunning.

    Heck, back in the 1960s, when I was reading all the giants of gun writing, those veterans were struggling with paper start/stop screens that had wires embedded in them and readouts on nixie tubes that had to be translated through tables to obtain velocities. Today, we have skyscreens that require no maintenance beyond awareness of where they are in relation to the muzzle, and our readouts are not only direct, they also store strings and perform useful statistics on them. Shooters who can’t calculate the mean for a string of numbers can print out the standard deviation of every string they shoot with the push of a button.

    All this comes at a price, and the price has never been lower. For about a C-note, you’re in the game with a Shooting Chrony Alpha chronograph that elevates you to the same level as puffed-up writers like me. I use the heck out of my Alpha model. Even though I own an Oehler 35P chronograph that’s well-respected as a scientific instrument, my little Shooting Chrony is handier and faster to set up and use. It gives me numbers just like the Oehler does, and it does all the simple statistics I need. And, thanks to the generosity of readers of this blog, I also have the optional Shooting Chrony Ballistic Printer for when the strings get really large and cumbersome.

    When should you buy a chronograph?
    This is the question each of us has to answer. The answer will be different for each person, but here’s what happened to me. I’d been an airgunner for 40 years before I bought my first chronograph. In my defense, most of those 40 years were the bad years for chronographs. Only in the last 5 to 8 years did the prices drop to affordability, mainly because the Shooting Chrony came on the market.

    Then, I started writing The Airgun Letter, and my need for a chronograph increased exponentially. When I started the R1 Homebrew series, the dam finally burst. How could I test the gun without one? So, at the 1993 Winston-Salem airgun show I bought a used Shooting Chrony from Paul Watts for $45. It worked fine and got me started with the R1 series, but that old model had cardboard skyscreen portals that were chewed up when I got the unit and I began chewing them up even faster. Before several months had passed, I started getting spurious readings that were 150 f.p.s. off what I knew they should be. I tracked that to the floppy, shot-up skyscreen portals and to not holding the barrel of the rifle perpendicular to the skyscreens. Edith and I freaked out, because here I was telling the world about my test gun and suddenly I felt I couldn’t trust my test instrument.

    So, we popped for the Oehler 35P chronograph that every gun writer worth his salt uses. In those days (mid-1990s), you couldn’t publish gun velocities in a newsstand magazine unless they had been obtained with an Oehler of some kind. I still have that Oehler, and I use it a lot, but I use my modern Alpha Chrony even more for the reasons I’ve already mentioned. However, I’m glad I bought the Oehler when I did, because they’re no longer available new. The used prices are on the increase. Fortunately, I know of a brand-new in-the-box 35P that I would buy in an instant, should the need ever arise. It might cost me $700, but at this point my career depends on chronographs so much that I would bite that bullet without a second thought.

    I would still continue to use the Alpha Chrony, as I am advising you to do. Yes, the Oehler gives more precision and yes, it has a second circuit built in, so you get not one but two different readings with every shot. Here’s the difference between this top-of-the line chronograph and a Shooting Chrony. The Oehler may say a shot went 987 f.p.s., while the Shooting Chrony may say the same shot went 996 f.p.s. The Oehler, with its 4-megahertz clock speed is 40 times more precise than the Chrony with its 100-kilohertz clock, but the actual difference on the readout is what…7 f.p.s.? Here’s the kicker — neither number is exactly correct. The Oehler is just a little “more correcter” than the Chrony. Who cares? We’re talking 7 feet per second over a range of almost 1,000 feet per second. It’s like dandruff on a white coat — nobody will notice. Besides, if all you publish is the Chrony number, then that’s the velocity. Get it? Think about that for a moment.

    I know this report sounds a little like a rant and a lot like a sales pitch, and perhaps both of those are true. But, I read every week about shooters who haven’t got a clue what their guns are doing and I hurt, knowing they’re so close to ultimate awareness. For the price of a cheap springer, you can have the wool pulled off your eyes and join the growing number of shooters who cannot be fooled. Last story before I close.

    Over the years, I’ve watched tadpole airgunners develop into fresh young frogs with minds of their own. The young tadpoles start out swimming around aimlessly, not knowing what’s out there or understanding the difference between a harsh spring rifle and a smooth-shooting PCP. Then, as they read, discuss and learn, their legs begin to develop and they start transforming into the dark green amphibians I know they’ll become. Finally, they pop for a chronograph, and the transformation is complete.

    I read every week about shooters who haven’t got a clue what their guns are doing

    Within a month, they start trying to email me spreadsheets of numbers they’ve obtained with their new toy. The last vestige of their now-useless tail has withered and dropped off, and they’ve become what destiny ordained.

    Three years later, they’re fat bullfrogs with their own lily pads and dozens of airguns, a well-worn chronograph and a deep croaking attitude about airguns that can be heard across the internet. Can’t nobody pull the wool over their eyes no more — no sir! That’s when they cease being newbies and become colleagues.

    Please think about it.

    In August 2006, I wrote an article about the Shooting Chrony and why you’d need a chronograph. Please read it and watch the video at the end. The information there is different than today’s report, and it’s a good augmentation.

    A shrine built for a Feinwerkbau 124 – Part 13

    by B.B. Pelletier

    Part 12
    Part 11
    Part 10
    Part 9
    Part 8
    Part 7
    Part 6
    Part 5
    Part 4
    Part 3
    Part 2
    Part 1

    The November podcast has been posted.

    Before we begin, my buddy, Randy Mitchell, who was also the outlaw, Dakota, from Frontier Village (an amusement park in San Jose, California, from 1961-1980) sent me a photo from over 40 years ago. I was Casey Jones, the engineer who ran the railroad at the Village, and Dakota had put an obstruction across the tracks out in the badlands. When I stopped the train, he jumped me at gunpoint and forced me to clear the rails. Then, he stole my boots and drove the train back to the station himself. How time flies!

    Dakota forced me to clear the obstruction, then stole my boots and drove the train back to the station himself. I had to walk back!

    Now, on to today’s report. Well, well. How the tide turns when you go to an airgun show! I went to Roanoke hoping to score an FWB 124 to tune and instead I picked up one to tune for somebody else. That’s usually a good thing, because when I tune for other folks I do a better job. I’m like the cobbler whose children are barefoot.

    You’ll remember from Friday that this rifle is Mark Taylor’s, and I gave you an idea of how it performed. The cocking was too hard, plus there was a scraping or grinding feel to it. Well, once I got the guts out I found out what that was and why it happened. But, I’m getting ahead of myself.

    The first comment I’ll make is that Mark’s rifle hasn’t been apart many times. The mainspring I removed looked like a 124 mainspring, except that it had 39 coils — and a standard spring I have has only 35. So, the spring I removed was much longer than standard. At least I think it’s longer. Heck, it’s been so many years since I tuned a 124 that I doubt I know anything for sure anymore.

    Looking through the cocking slot before disassembly, you can see that the mainspring has been coated with moly grease.

    The second comment is that Mark’s rifle had the strangest lubrication I’ve ever seen in any spring rifle, and I include my older San Anselmo rifle in that observation. My gun was tuned back in the day when it was standard practice to use an entire jar of Beeman’s moly grease on the mainspring of a 124. When I took that gun apart the first time, I was scraping grease from everywhere! Had I known how full it was, I could have called Mike Rowe and gotten him to put it on his Dirty Jobs TV show.

    In contrast, Mark’s rifle was almost dry inside! Only the mainspring was coated with moly, and it looked like a smear of lithium grease might have been applied to one spot on the back of the piston. As a result, the piston was touching the top of the spring tube when the gun was cocked and had galled (made shiny by removing a small amount of metal) a large area that wasn’t too deep. It wasn’t serious, but it also was never going to get any better.

    This is how the piston looked immediately after removing it from the gun. There’s no lube on the seal!

    This is the back end of the piston, called the skirt. As you can see, it has next to no lubrication.

    The scraping, grinding feel came from this area. Those two bright lines are galled metal, where the piston skirt scraped against the inside of the spring tube. The damage is minor and correctible with the proper lubrication.

    I discovered this lack of lube when I cleaned the inside of the spring tube. It was practically dry and grease-free in there. If I had tuned it, there would have been a lot of moly burnished into the metal and the cleaning patches would have come out black instead of white.

    Using moly grease on the mainspring isn’t the best thing when you want a smooth shot cycle. That’s where Maccari’s Black Tar comes into play. A dry piston isn’t the right thing for this gun, as evidenced by the galled metal. I lubed the front and rear of the heavy 124 piston with moly grease. Gene Salvino, Pyramyd Air’s tech manager, recommends using lithium grease on their piston seal, but I used moly on this one because of the galled metal.

    The piston seal that was in the rifle looked to be in fine shape. Since this was supposed to be a test of the new Pyramyd Air seal, I removed it anyway. I’ve never seen another one like it and have no idea where it came from.

    I also noted that the baseblock bearings weren’t lubricated with much of anything, which might have added to the cocking effort. Also, the barrel pivot pin was dry. I spread moly grease on both the bearings and the pivot bolt before installing them in the rifle again.

    I selected an old Maccari Deluxe tune kit for the rifle. This kit drops in, but is made so perfectly that the mainspring goes on the spring guide like it was nailed on. That’s tuner’s slang for a very tight fit. The spring diameter expands when it’s compressed lengthwise, so the fit isn’t as tight as it seems when you install it. There was also a Delrin spacer for the spring guide that put a little more tension on the spring.

    This is how to lubricate a 124 piston correctly. Both the front and rear of the piston can contact the other metal surfaces inside the gun. The center of the piston is smaller and cannot touch anything. Besides this, I also burnished moly inside the spring tube before installing the piston.

    All metal-to-metal contact surfaces except for the outside of the mainspring got a coat of moly grease before the gun was assembled. The outside of the mainspring was buttered with Black Tar. Then, the gun was assembled in reverse order from disassembly.

    This is how I “buttered” the mainspring with Maccari’s Black Tar mainspring dampening compound.

    On to shooting
    The proof is in the shooting, and the first time I cocked the assembled rifle it worked as it should, which doesn’t always happen. I noted that the cocking effort didn’t seem to have decreased much, but the cocking cycle was now as smooth as it should be. Then, I shot the rifle.

    Wow! What a beautiful tune this is. Not only is all vibration gone, but the forward recoil I had noticed disappeared, as well. The gun just sort of pulses when it’s shot.

    I then measured the cocking effort and was stunned to find it had increased a pound to 28 lbs. of effort. Personally, I think it’s too heavy for a 124, but the smooth shot cycle is too nice to ignore. Let’s see what is does over the chronograph.

    Crosman Premier lites
    The 7.9-grain Crosman Premiers averaged 744 f.p.s. with this tune. The spread ranged from 736 to 750 f.p.s. That’s a little tighter than the original tune, and much smoother. The average muzzle energy was 9.71 foot-pounds.

    RWS Hobbys
    RWS Hobby pellets averaged 784 f.p.s. The spread went from 776 to 793 f.p.s. Again, a slightly tighter spread than before. The average muzzle energy was 9.56 foot-pounds, and a super-smooth shot cycle.

    JSB Exact 8.4 grains
    JSB 8.4-grain Exact domed pellets averaged 723 f.p.s., a surprisingly low figure. They ranged from 713 to 730 f.p.s. and produced an average muzzle energy of 9.75 foot-pounds. They shot just as smooth as the other two pellets.

    What to do next?
    This is a toughie. The rifle is cocking and shooting extremely smooth right now, but the cocking effort is a bit high. Mark, the owner, says he doesn’t mind that, as long as the gun shoots smooth, which it definitely does. I’m at the point of a decision that I’m going to let Mark make. I feel certain that the Black Tar on the mainspring is what’s slowing down the gun just a bit. As tight as the mainspring fits, it probably isn’t necessary. Still, the gun does shoot very smoothly, and almost all of the forward recoil seems to be gone, as well. From a shooting standpoint, this is a fine tune. I’ll let Mark decide.

    If he wants more power for the cocking effort, I would remove the Black Tar and lube the mainspring with moly grease. But, if he wants a super smooth shot cycle, we have that right now.

    Mark, what would you like me to do?

    A shrine built for a Feinwerkbau 124 – Part 12

    by B.B. Pelletier

    Part 11
    Part 10
    Part 9
    Part 8
    Part 7
    Part 6
    Part 5
    Part 4
    Part 3
    Part 2
    Part 1

    Before I start today’s report, Joe B. in Marin and Duskwight were really impressed by that air bazooka I showed on the blog for Day 2 of the Roanoke airgun show , so today I included a picture of the ammo. Duskwight — all U.S. bills are the same size, so those projectiles are very large.

    Two of the air bazooka projectiles from the Roanoke airgun show dwarf a dollar bill.

    Well, this report has taken on a life of its own! I never intended for it to grow this huge, but things just kept popping up and I had to address them. Today was supposed to be my report about tuning my San Anselmo gun once again with the new Pyramyd Air piston seal, but something strange happened at the Roanoke Airgun show to change that.

    When Pyramyd Air assumed responsibility for the high-end Beeman airguns, they had this piston seal made for the FWB 124. It’s a 70-durometer material with a good parachute channel. I’ll install it in a 124 and report my findings.

    This seal is also available from Pyramyd Air, although I don’t think it’s online yet. They’re using them so fast that they’ll soon make another run of seals.

    Mark Taylor, a reporter for the Roanoke Times, wrote a nice piece on the show that Edith sent to me while I was on the road. Mark stopped by my table to introduce himself. As we chatted, he asked me if there were any airgun tuners who could tune his FWB 124 to shoot smooth. Of course, Paul Watts was at the show, but Mark knew that Paul has a long waiting period, and he wanted his gun back as soon as possible.

    So, I thought, “Why don’t I tune his rifle?” Then, I won’t have to open up mine one more time. Mark’s rifle has a 38,000 serial number, so the tight compression chamber shouldn’t be quite the problem that it is on mine.

    Mark went out to his car and got the rifle for Mac and me to examine. It’s a deluxe model in excellent condition. When we cocked it, we both knew something dreadful was wrong. It cocks much harder than a 124 should, and there’s a grinding feel to the mainspring as it’s compressed. Today, I’ll shoot the gun for a baseline, then in the next report I’ll pull it apart for a look-see and a smooth tune.

    From the feel of the cocking effort, I believe someone has tuned this rifle for power and left smoothness to suffer. The chronograph will tell the story, of course. If I’d experienced this 124 as the first 124 I’d ever seen, I would have thought all the wonderful reports about it were lies. The cocking effort is a whopping 27 lbs., which is about right for a Beeman R9 but quite a bit too heavy for a 124.

    Mark stressed that all he wanted from his rifle was smooth shooting. Well, the 124 can certainly deliver that in spades, and it doesn’t have to give up much in the way of power to do so! While Mark was at my table, Mac picked up a 124 from a table nearby and showed Mark what the gun should feel like. The difference was night and day.

    The rifle test
    This rifle cocks with a gritty, rubbing feel. Through the cocking slot, I can see what appears to be moly on the spring, so the gun has definitely been opened up at some time. I wonder what I’ll find inside?

    Crosman Premier 7.9-grain pellets
    The standard test pellet is a Crosman Premier 7.9-grain domed pellet, because it’s the one more shooters choose for their accurate airguns. Mark’s 124 was shooting this pellet at an average of 761 f.p.s. as it was tuned. The spread went from a low of 752 f.p.s. to a high of 770. That’s an 18 f.p.s. total spread, which isn’t too bad. The average muzzle energy is 10.16 foot-pounds

    RWS Hobbys
    The next pellet I tried was the RWS Hobby. At 7 grains, it’s among the lightest of the pure lead pellets. Hobbys averaged 808 f.p.s., with a spread from 798 to a high of 819 f.p.s. The average muzzle energy for this pellet is 10.15 foot-pounds

    JSB Exact 8.4-grain pellets
    For some reason, JSB Exact domes weighing 8.4 grains were the most powerful of all. They averaged 764 f.p.s. with a spread from 757 to 777 f.p.s. The average muzzle energy is 10.89 foot-pounds.

    While I shot the rifle over the chronograph, I felt the harshness of the powerplant. The vibration was quick and powerful, and the forward lunge of the rifle that’s a trademark of the 124 was quite noticeable. I won’t be able to cancel that out, but I should be able to get rid of all the vibration and the scraping feeling when cocking.

    Now that I have a baseline of performance, I can pull this rifle apart and see what’s inside. It’ll be a pleasure to tune this rifle sweet for Mark so he can feel how a 124 is supposed to behave. That’ll be in the next report.

    A shrine built for a Feinwerkbau 124 – Part 11

    by B.B. Pelletier

    Part 10
    Part 9
    Part 8
    Part 7
    Part 6
    Part 5
    Part 4
    Part 3
    Part 2
    Part 1

    Well, here is our old friend, the San Anselmo Beeman 124, again. Today, I’ll address the scope problems I was having the last time I tested the rifle for accuracy.

    You may recall that I suggested that the front and rear rings be swapped to see if that would alter the amount of down angle the rifle appears to have. One reader was appalled that anything manufactured could be that far off from true, but believe me, it doesn’t take much. I’ve seen this trick work many times in the past. However, I failed to mention that three inches is a bit excessive to try to correct this way. This trick is more for those who optically center their scope and have a half-inch problem at the first point of intersection.

    However, I did remove the rings and swap the front for the rear. Because these are two-piece rings I could also turn one ring at a time, giving me six different permutations of the setup, I believe. But three inches of change is so major that if it doesn’t come by swapping positions, you might as well look elsewhere.

    Well, I was right. Swapping the rings did make a big difference. Only the difference went the wrong way. Now the pellet was striking the target four inches below the aim point, using the exact same scope with no adjustments. So, this set of rings was history. No amount of shimming would ever be able to make up an angular difference that large.

    However, I had an ace up my sleeve. I’d visited the AirForce factory and asked to borrow a BKL drooper scope mount, and they happily complied. So, now I had the BKL 260 with .007 drop compensation to try out. This is a one-piece mount and it comes with simple instructions for which way to mount it. However, I did encounter a problem. This BKL mount is too low to allow the 50mm scope I had been using to clear the 124 spring tube. And you’ll recall that I have to use a BKL mount because of the 124′s non-standard scope stop system. I have mounts that will work with it, but you can’t buy them, so I’m not testing them here.

    The solution was to use another scope, and all I was trying to do was ascertain that there was a scope mount and ring set in the world for this rifle — a vintage 124 with a large barrel droop. So, I picked a BSA 3-9×32 scope that didn’t have parallax adjustment. As a result, I had to run it at five power or the target was too blurry to see well.

    The BSA scope fits well in the BKL drooper mount. I could have gotten away with a 40mm objective, if I’d wanted.

    Even with all that disadvantage against me, I proved the concept. The 124 and this new scope adjusted on target perfectly with no problem of adjusting the elevation knob too high.

    So, I shot one group of 10 Crosman Premier 7.9-grain pellets and then another. Sure enough, the problem has been solved.

    Good group, properly centered and 10 tight shots at 25 yards with Crosman Premier lites.

    I’m removing the scope from the gun, because the only reason I scoped it in the first place was to conduct the Silver Jets accuracy test. That’s over now, so the 124 can go back into its sarcophagus, except for one more tuneup that will employ the newest Pyramyd Air 124 piston seal.

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