Spring-piston rifles

Airgun lubrication — spring guns: Part 1

by Tom Gaylord, a.k.a. B.B. Pelletier

Today, I’m starting a long series on lubricating airguns. Blog reader Joe asked for this; but as I was researching the subject, I stumbled across another request that came in through the customer reviews on the Pyramyd Air website:

“I wish that RWS or Pyramydair would explain the process and frequency of oiling these RWS rifles in particular the RWS mod 48. Everyone I talk with says the RWS owners manual is outdated and that with the new seals they use does not need to be lubed maybe for years….I purchase the RWS chamber and cylinder oil at a cost of almost $30.00 and now am told I probably will never need it? This topic should be cleared up once and for all by the manufacturer.”

Perhaps this customer is referring to RWS Chamber Lube and RWS Spring Cylinder Oil as the two products he purchased. And they do add up to $28 before shipping. Are they necessary? Should he have bought them? That’s the question I’ll start answering today.

This subject is so vast and complex that I cannot address it in a single report. In today’s report, I’m only going to look at lubricating the piston seal. That constitutes about half of the lubrication requirements for many airguns, in my opinion. In the next installment, I’ll address all other spring gun lubrication, including the mainspring and piston.

Leather piston seals
In a spring gun, the piston seal is what compresses the air when the gun fires. As the piston goes forward, the seal keeps the air in front of the piston, where it gets compressed because the only escape is blocked by the pellet sitting in the breech. If the gun’s working properly, all other avenues for the compressed air to escape have been blocked.

In the past, pistons were sealed with a leather pad or cup. Leather is an ideal material for this job. It’s rugged, lasts a long time and will conform to the shape of the compression chamber after a few shots — much like a leather shoe that eventually fits your foot perfectly.

leather piston seal
This cup-shaped leather piston seal is for a Chinese spring rifle.

To do its job, a leather seal has to stay soft and pliable, and oil is the best thing for this. As the spring gun operates, a little of the oil is consumed with each shot, so a leather seal needs to be oiled frequently to stay soft. How frequently? In some older guns, I’ve found that oiling every few weeks is necessary if they’re shot a lot. Certainly, all guns with leather seals need a couple drops of oil at least once each month if they’re to be shot. You can leave a gun with leather seals unoiled for years if you don’t shoot it; but before you start shooting it again, that seal needs to be oiled. When I start shooting an older gun that I know has leather seals (I use references for finding out things like this), I put about 10 drops of oil through the air transfer port and let it soak into the seal for at least an hour, although a half day is even better.

What oil to use?
The type of oil you use depends on the velocity of the gun. Guns that shoot less than 600 f.p.s. in both .177 and .22 caliber will be oiled with regular household oil. Any petroleum-based lubrication oil will do. Yes, gun oil will also work. For guns that shoot faster than 600 f.p.s., I use silicone chamber oil, like the product listed above. The spring cylinder oil is not for chambers and should not be used on the piston seals of these guns.

Synthetic seals
Starting in the 1950s, manufacturers began experimenting with piston seals made from synthetics. Some of them, like the ones used by Anschütz and Falke, worked well and lasted for many decades. But others, such as the seals used by Walther on all their airguns and the seals that Feinwerkbau used on the 121 and 124/127 sporting rifles, were made from a material that dry-rotted within about 20 years. If they were oiled by anything, they failed even faster. These seals started out as a light beige color, but as they absorbed oxygen and oil, it turned them dark yellow and brown until they began to break apart in waxy chunks.

Diana was one of the last companies to switch from leather to synthetic, and they had the benefit of watching the others. They were still using leather seals in their powerful model 45 rifle in the late 1970s, at a time when that airgun had broken the 800 f.p.s. “barrier.” When they started making synthetic piston seals, they used a blue-colored material that was tough and long-lasting. It’s interesting to note that the others adopted similar piston seal material when they finally realized their seals were perishing in use.

Diana piston seal
The blue Diana parachute seal is so rugged that hobbyists use it for many other airguns. It needs very little oil!

modern FWB piston seals
These 2 FWB 124 seals are made from modern synthetic material, yet they look like the original ones. The one on the right has been inside a rifle for a few thousand shots. It looks bad but is still in great shape and will last for many decades.

Don’t fixate on the color blue for piston seals! These synthetics can be colored any way and still be fine. I have modern FWB 124 seals that look similar to the old seals in color, yet they’ll last indefinitely. It’s the material, not the color.

Which oil to use?
With synthetic seals, I always use silicone chamber oil. That’s SILICONE CHAMBER OIL — not brake fluid, silicone spray lubricant or any other concoction. Chamber oil is for piston seals. It does not lubricate metal parts because the viscosity is too low. It’ll ruin metal parts if you use it that way. On the other hand, nobody knows what will happen to a gun that’s lubed with anything other than SILICONE CHAMBER OIL.

Diana recommends using two drops of chamber oil on the piston seal every 1,000 shots, and one drop on the breech seal at the same time. That’s it. To answer the person who asked if he needs the chamber oil, the answer is yes. But one small bottle will last a long time. I’ve observed that most Diana airguns can get by with even less oiling than what’s recommended. One diagnostic for when a gun need its seal oiled is when the seal honks like a goose as the gun is cocked.

Silicone chamber oil has a high flashpoint. Since the air in a spring-piston gun reaches about 2,000˚F with every shot, this is important. This heat is adiabatic — it doesn’t heat the gun because the interval is too brief.

Overlubing vs. underlubing
It’s almost impossible to overlube a leather piston seal. And it does not harm the seal if you do.

On the other hand, overlubing a synthetic seal can start the gun detonating. Not dieseling — most spring guns diesel. When you smell burning oil, your gun’s dieseling. Dieseling is just a few oil droplets vaporizing with each shot. It’s perfectly normal in a spring gun.

Detonation is when a lot of droplets vaporize and cause an explosion. That will damage your piston seal if it’s allowed to continue for a long time. It can also break your mainspring.

So, dieseling is okay, but detonations are bad. And overoiling synthetic seals causes detonations.

Do you see why I had to cover just the piston seals today?

BSA Supersport SE: Part 2

by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1

BSA Supersport SE
BSA Supersport SE

Let’s look at the velocity of the BSA Supersport SE. The factory advertises 750 f.p.s. for the .22-caliber rifle I’m testing. I just hope that’s with lead pellets.

Cocking effort
I mentioned in Part 1 that the rifle cocks a little on the heavy side. I estimated 40 lbs. of effort. On my bathroom scale, this one actually requires 39 lbs. to fully cock the rifle. My gut tells me that some of the effort is the tightness of the new gun and will probably decrease by a few pounds over time.

I cannot resist making a comparison with the Beeman R9, which is also sold as the HW 95. The size and power of this rifle seem to align with that classic, but shooting will tell us the whole story.

RWS Hobby
The first pellet I tested was the RWS Hobby – a lightweight lead wadcutter that’s used to test the legitimate velocities of all airguns. By legitimate, I mean that there are many lead-free pellets that may go faster; but since very few of them are accurate, they probably won’t be used by many shooters.

Hobbys averaged 717 f.p.s. from the test rifle. But the velocity spread was large — from a low of 695 f.p.s. on the final shot to a high of 731 on shot three. That’s 36 f.p.s., which is a bit high for a springer — especially these days when many new spring guns come out so well adjusted.

At the average velocity, Hobbys generated 13.59 foot-pounds of muzzle energy. Hold your comments, however, because I noted in Part 1 that I thought this rifle might have a heavy piston (or top hat) that I said could make it shoot better with heavier pellets. So, let’s try one.

Beeman Kodiak
The next pellet was the 21.14-grain Beeman Kodiak — a heavyweight if ever there was one. Kodiaks averaged 535 f.p.s. in the test rifle, and the spread was just 12 f.p.s. It ranged from 527 f.p.s. to 539 f.p.s. At the average velocity this pellet produced 13.44 foot-pounds of muzzle energy. Not as much as the Hobby, but very close. And the tight velocity spread leads me to suspect I was right about the piston. I think the Kodiak has earned a spot in the accuracy test.

RWS Superdome
We need to see what a medium-weight pellet can do in the Supersport SE, and the RWS Superdome is a fine one to try. At 14.5 grains, it sits right in the middle of the weight spread — especially in the range of pellets that should be considered for this rifle.

Superdomes averaged 661 f.p.s. in the Supersport. Since we know the “magic” number is 671 f.p.s. — where the weight of the pellet in grains equals the muzzle energy in foot-pounds — we are very close to that level. This rifle must therefore produce a shade less than 14.50 foot-pounds with this pellet. And it does! It produces 14.07 foot-pounds of energy at the muzzle — the highest energy of the three pellets tested.

The total velocity spread for the Superdome was 16 f.p.s. Therefore, the 2 heavier pellets did better (shot more stably) than the lightweight Hobby. I’ll keep that in mind as I test the rifle for accuracy. Yes, I will test it with a scope; but since it comes with a nice set of open sights, I plan to first test it with them.

General comments
The rifle cocks smoothly and without the normal noises I associate with a new spring rifle. And when it fires, there’s no objectionable vibration, as long as you hold it lightly.

The trigger is reasonably crisp. It breaks at 2 lbs., 14 oz., which is light but not overly so. I also really like the fact that the safety is manual.

Last comment. The Supersport SE feels very “old school” to me. It isn’t overly powerful. It has a smooth cocking and shooting sequence. And the size and weight of the rifle feel very nice. I’m so tired of those oversized breakbarrels that make me feel like I’m a kid shooting dad’s big shotgun for the first time. The Supersport SE feels just right.

Odds ‘n’ ends

by Tom Gaylord, a.k.a. B.B. Pelletier

I’ve wanted to write a blog about several different subjects for a long time, but I didn’t know what to call it. What I’ll do today is clear the boards of a couple small, unrelated things.

American Airgunner
As you know, I spent most of last week in Ft. Smith, Arkansas, filming the 2014 season of American Airgunner. I’m in a segment of the show called “The Round Table,” where a bunch of guys talk about different subjects. This year, we did some hands-on work that was more exciting than last year, but I’m not going to tell you what that was. You’ll just have to watch the show like I do!

We worked with 5Star Productions — an award-winning video production group based in Ft. Smith. I’ve worked with several video companies over the years, and I can tell you that these guys are first-rate! We knocked out all 13 episodes in three days of filming and even shot some bonus footage because they were so efficient. Getting out of the office is hard for me these days, and it’s such a pleasure when I get to work with professionals who know exactly what they’re doing!

American Airgunner studio
The Round Table set on American Airgunner.

On the last day, we filmed on location at a large ranch in Oklahoma. The four of us — show host Rossi Morreale, Steve Criner, Rick Eutsler and me — were very loose and somewhat tired. Rossi was talking to Steve about how he seemed to change whenever he was on camera. And that’s when this happened: Behind the scenes outtake.

Now, on to the blog.

I got this new airgun and…
Pyramyd Air gets a lot of customer feedback about the guns they sell. Recently, a gentleman wrote in to complain about the accuracy of a Crosman Fury Nitro Piston rifle he’d purchased. He said he was a 1,000-yard benchrest shooter, so he knew how to shoot, but he could not get the Fury to group.

No kidding! I bet he also couldn’t get a rack-grade Marlin 30-06 to shoot well at at 1,000 yards — either! And Corvettes make lousy pickup trucks!

Come-on, guys. When is a $120 breakbarrel springer ever going to give you dime-sized groups at 30 yards? Maybe the Air Venturi Bronco can do it, but not too many others. And, when you stuff a gas spring (the Nitro Piston) into a budget-priced rifle, it’s going to push everything way beyond the limits. Sure, it’ll work, and you may get wonderful velocity numbers. But tight groups? I think not.

Pyramyd Air, however, gave the gentleman the more civilized answer.

A few things to try. (1) Your gun may have barrel droop and might benefit from an adjustable mount that helps compensate for droop. (2) Try JSB or H&N domed pellets. You should see a significant difference. When it comes to pellets, you get what you pay for. (3) Tighten all stock screws. You’d be surprised how many guns have loose screws after just a few minutes of shooting. Many people use blue Loctite on their gun screws so they don’t have to stop shooting every few minutes to tighten the screws! (4) Springers often require a break-in period. Many people don’t see consistent groups until 500 or even 1,000 shots. In fact, when Dr. Robert Beeman owned Beeman Precision Airguns, he stated in his catalogs that springers needed 500-1,000 shots. While springers these days may not need quite that many, they DO need some break-in time. If you don’t have a lot of shots thru your rifle, you may want to put some pellets downrange to see if accuracy increases. (5) Lastly, how about using another scope? Not all scopes are created equal. Get a different scope (one that you know has good glass and can stand the 2-way recoil of a springer) and see if accuracy improves. Hope these suggestions help.

These are all things that experienced airgunners do with any new rifle they get. We expect to have to do them and are pleasantly surprised when we discover that one or more of those things isn’t required. But the bottom line is what I said at the beginning. Don’t expect inexpensive airguns to group tight — and be very thankful if they do.

I can’t win
I recently tested a Daisy 880 and got criticized for not testing a brand new gun. I was told that my reviews influence a lot of people, and I should always test new guns that represent exactly what the customer will get.

When I write a report I put a lot of words into the article. It this particular report I wrote the following words:

The rifle I’m testing for you is about 13-14 years old, but it probably has fewer than 500 shots on the clock.

That means the rifle I’m testing is not new. I imagine my readers don’t always know what I do, but they can read and understand what I’m saying.

In the second report, after showing the velocity numbers and remarking that the velocity varied widely, I said:

The Daisy 880 varies greatly in velocity from test to test. You may think this is because my 880 is an older one. I can’t argue that. If you want to run the same test with a more modern 880 and submit your results, I’d be glad to see them; but please back up any claims you make with chronograph results.

I wrote that paragraph so the readers would know the possible reasons why the gun I was testing was acting like it did. I never anticipated that anyone would use parts of each of my reports as material for a debate on ethical writing! But, seeing that it happened, I thought it was important to point out everything that was said.

Some folks worry too much about the other guy, and forget to watch over themselves. I like to let each reader ask his own questions and not let one reader speak for a group that may or may not exist.

However, there was enough discussion on this topic that I requested a brand new Daisy 880 from Pyramyd Air, which I’ll test when the test of my old rifle is finished.

This sort of thing sticks in my craw because it happens both ways. When an older rifle doesn’t do as well as it should, I get criticized for testing it. And, when an older rifle does better than it should, I’m told that I shouldn’t test an airgun that is so well broken-in. That happened when I tested my TX200 Mark III. I was told that my older rifle shot faster because it was so well broken-in. Now, I’m told the Daisy 880 shoots so poorly because it’s an old air rifle.

You know what I think? Air Arms guns get better with age — or at least that’s what people think. And Daisys wear out over time, or at least that’s what people are saying. Maybe there’s some truth hidden there?

When I get this new airgun, where should I get it tuned?
This comes up all the time. People buy a brand-new airgun; and, because of the reading they’ve done, they assume it has to be tuned to work for them. I’ll admit there’s some wisdom in this philosophy, but I think something more needs to be said. Why not shoot the gun awhile just as it comes? I have a story to illustrate this.

Many years ago, I bought a Ruger 10/22 rimfire rifle for an article I was writing on silencers. But I figured I could test the rifle in different ways and get even more stories out of it. Well, the story I got turned out to be quite different from the one everyone thought.

My late friend Mac had a 10/22 that was a tackdriver. He’d sent it to Connecticut Precision Chambering for a target chamber, a headspacing job and a trigger job and reckoned they could do the same for me.

When I first tested that rifle, it wasn’t that accurate. It grouped about 1.5-inches for 10 shots at 50 yards with the best ammo available. I was glad to send it off for the work. I figured this was how Mac had gotten his rifle to become so accurate. When it came back, the trigger was wonderful, but the rifle still wasn’t that accurate. Ten shots would now group a little larger than one inch at the same 50 yards.

This puzzled Mac, who was sure my rifle would become a tackdriver after the customization. A tackdriver would put 10 shots into about a half-inch at 50 yards. I still own that rifle, and it’s never done better than an inch for 10 shots. But I bought an aftermarket 20-inch Badger bull barrel for it that gives 10-shot groups under 0.6 inches at 50 yards. Then I acquired a Ruger 10/22 Target rifle that has a hammer-formed barrel, and that one would put 10 into 0.540 inches at 50 yards with the best ammo.

Now, about 12 years after all of this has passed, I recently chanced to pick up a 10/22 Deluxe in a trade at a gun show. The Deluxe is the standard rifle but with a walnut stock that’s checkered and a bolt that’s polished. The trigger is still hard and creepy. When I shot it I was amazed. Finally, I have a 10/22 that’s a potential tackdriver right out of the box. No, it hasn’t put 10 into a half-inch yet, but it has certainly gone under an inch with no modifications.

Here’s the point I’m making. Before you invest serious cash in any gun, make sure it’s got good bones to begin with. Otherwise, you’re just putting lipstick on a pig.

Air rifles that made an impact: Part 1

by Tom Gaylord, a.k.a. B.B. Pelletier

Today’s topic was suggested by Dennis Quackenbush. We were discussing the influence made by a few key firearms, and he wondered if I’d ever written about airguns in the same vein.

The title says it all, and I bet a lot of you can start a list right away. But which ones to pick? It’s easy to speculate and guess, but is there a better way to choose the air rifles that really did make an impact? And what is meant by “impact?”

I find that an easy way to approach a monumental subject like this is to step away from airguns and choose something that many more people can relate to. Like automobiles, for instance. Which automobiles had an impact on the entire motoring universe?

Well, you can’t go very far without recognizing the Ford Model T. In production from 1908 through 1927, the model T put America on wheels. It caused roads to be paved, businesses to spring up in unlikely places and the entire demographic fabric of the United States to change forever.

When the flivver (as it was also called) first came out, politics in the U.S. were most important at the county level, then the state and only grudgingly at the national level. When it finally passed from the market, national politics were forever changed and local elections were relegated to the status of “also ran.” The Tin Lizzy got the farmer off his farm and into town as frequently as every weekend.

And, if the 15 million Model Ts were game-changers, what about the more than 21 million Volkswagen Beetles that swarmed over the planet from 1947 until the last one was built (in Mexico) in the early 21st century? Certainly, they had a major impact on personal transportation? [I know the Beetle is still being produced, but I'm talking about the original air-cooled version.]

See how easy this is when the topic isn’t as important as airguns? Now, name an air rifle that changed the game.

BSA
How about the very first modern air rifle that was conceived in 1905? Built by the Birmingham Small Arms company, best-known for their military rifles, the first underlever air rifle that came to market was called the Lincoln; but BSA liked what they were contracted to build and they put their own name on the rifle, as well. That one rifle started the entire line of smallbore airguns we enjoy today.

There were pellet guns before the BSA, of course, but they were primarily smoothbores and made to shoot darts. Their construction wasn’t robust like the BSA’s was, and they were entirely unsuited to the type of shooting we do today.

One of our own blog readers — RidgeRunner — picked up a 1906 BSA at the Roanoke airgun show last year. Maybe he’ll favor us with his impressions of this hugely important airgun?

BSA 1906
This BSA underlever was the first modern air rifle.

FWB 124
It came along in the early 1970s and metamorphosed in front of our eyes. Originally it was nothing more than a well-made sporting breakbarrel, the 124 (or 121, as it was first known) had a longer piston stroke than any gun that went before. No doubt, the German engineers were just interested in keeping the cocking effort to a minimum; because in their country, the muzzle energy of airguns is limited to 7.5 Joules by law. A longer stroke meant they could use a less powerful mainspring and still get the velocity they were after, but it also meant the gun was primed to be hot rodded.

By the end of the decade, the 124 had become the first air rifle to break the 800 f.p.s. “barrier.” Several other companies — notably BSF and Diana — followed suit; and by 1979, the airgun velocity wars were in full swing.

FWB 124
The FWB 124 started the airgun velocity wars in the 1970s.

Beeman R1
I’ll never forget seeing the Beeman R1 in the Beeman catalog. I had just purchased an FWB 124 and thought I was king of the hill, only to discover that the new R1 had 140 more f.p.s. I was livid! And within a year, Beeman was offering a special tune that jacked up the velocity over 1,000 f.p.s. — the first spring gun to do so. In another year, the standard R1 was getting 1,000 f.p.s. out of the box, and the special tune got them above 1,100 f.p.s.

The R1 didn’t stay on top for very long. Diana soon came out with their model 48 sidelever, which produced an honest 1,100 f.p.s. out of the box…and did so with less cocking effort than the big R1. But for as long as it reigned supreme, the Beeman R1 was like a booster rocket for the advancement of the spring-piston air rifle.

Beeman R1
Beeman’s R1 accelerated the velocity wars beyond the sound barrier!

Are there others?
Of course, these 3 rifles aren’t the only ones to have a major impact on airgunning. I can think of several that belong in this group. What models do you think deserve this recognition? And why?

What is a top hat? Exploring the guts of a spring gun

by Tom Gaylord, a.k.a. B.B. Pelletier

Last week, I made reference to a heavy top hat affecting performance in a spring gun, and blog reader Joe asked this question:

“You wrote ‘…weighted top hat inside the piston, or the piston itself is heavy. Either way, the rifle should shoot medium and heavyweight pellets better than lightweight pellets.’

What is a ‘top hat’? Why would a heavy piston or top hat shoot medium to heavy pellets better?”

Joe, thank you for asking this question. This blog is now in its 10th year, and I forget that the readership has changed over that time. If one person asks a question, it means that many other readers are wondering the same thing and not writing in. Today, I’d like to review the main parts of a spring-piston airgun powerplant and discuss how they affect performance.

Piston
The piston is the most recognizable part of the powerplant. When the gun fires, it’s propelled forward by some kind of spring. It may be a coiled steel spring or it could be some kind of gas under pressure — whatever the source of energy is, it pushes the piston. And before anyone asks — yes, there have been guns with springs that pull the piston.

The piston compresses air in front of it as it goes forward. There is some kind of seal on the piston that keeps most of the air contained, so it compresses air very well.

spring piston seal detail
The piston seal (this one is a parachute type, whose sides flare out and seal the chamber better) seals the air in front of the piston.

Tuning tip
Removing excess tolerance makes a spring gun shoot smoother. The top tuners put Teflon or nylon bearings (called buttons) around the rear of the piston skirt to hold it steady and away from the spring tube walls. The piston seal does the same thing for the front of the piston. In a well-built airgun, the metal piston should never touch the walls of the spring tube.

Nitro Piston 2 buttons
These small white nylon bearings on the Benjamin Nitro Piston 2 are part of the reason that rifle is so smooth when it fires!

Compression chamber
Let’s talk about something that’s dirt-simple, yet confuses a lot of people — the compression chamber. It’s the end of the spring tube, which has been closed off by a metal cap. A hole through the cap, called the air transfer port, allows the compressed air to move from the compression chamber to the barrel. If there’s a pellet in the barrel, the air cannot get past it and has to shove the pellet out of the way. This doesn’t happen until the air reaches a high pressure, which is at the heart of today’s discussion. Essentially, the pellet stays put until the piston has come to almost a full stop, then the compressed air blows it forward, like the cork from a champagne bottle.

spring piston powerplant
The spring-piston powerplant is so simple that it confuses people.

Spring
We all know what the spring does. It pushes the piston, which compresses the air. A spring can be either coiled steel or compressed gas; but for the remainder of this report, I’ll be talking about a coiled steel spring because it’s the thing that relates to the top hat.

spring inside piston
Thanks to a generous cocking slot, we can see the mainspring inside this piston’s body.

Spring guide
The spring guide does what the name says — it guides the spring. What it actually does is keep the coiled spring from twisting or bending too much as it’s compressed.

spring guide inside spring
This is the spring guide. It’s hollow to allow the piston rod to pass through when the gun is cocked. The metal one is an older Beeman R1 guide, the white plastic (probably nylon) one is what they use more often these days. A lot of vibration can be eliminated by very closely fitting this guide to the inside of the spring.

When the gun is cocked, the piston comes back and compresses the spring. The spring fits up inside the piston, so it’s contained by the piston skirt as the piston comes back over it. The spring guide is a hollow tube at the rear of the spring that the spring fits over. As the spring is compressed, it tries to bend to the side, but the spring guide prevents it. The piston skirt keeps it from bending at the front.

Tuning tips
When a tuner wants to smooth the performance (the shot cycle) of a spring gun, getting rid of excess clearance is a great way to eliminate vibration. The outside of the mainspring is fitted to the inside of the piston skirt very closely. Here’s something you may not have guessed. When the spring is compressed, it also expands just a little (measured in thousandths of an inch), so the internal fit to the piston skirt has to take that into account.

The spring guide is also fitted to the inside of the mainspring. In the best-tuned airguns, the guide cannot be put on the spring unless the spring is twisted against the guide counterclockwise. Airgunsmith Jim Maccari calls that a guide that’s “nailed on.” The mainspring grows in diameter as it’s compressed. When the gun is cocked, the spring loosens a little and slips down the guide.

Top hat (forward spring guide)
Okay — here it is. You had to wade through lot of blather to get to this point, but I hope it’ll be worth it. A top hat is a spring guide that is on the front side (the piston side) of the spring. It fits inside the piston and slides on the central piston rod. Obviously, the mainspring fits over this guide, too, just like it fits the guide in the rear.

top hats and spring
Two top hats (forward spring guides). The heavier one at the bottom was made by airgunsmith Jim Maccari for a special Beeman R1 tune that worked for heavier pellets. I wrote about it in the “Beeman R1″ book.

Tuning tip
Joe — this is the answer to your question. A top hat adds weight to the piston. A heavy top hat adds a lot of weight.

When the piston compresses the air in the chamber, it can reach very high pressure before the pellet starts moving. When the pellet begins to move, the air pressure drops rapidly. Although the pressure is very high, there’s not a lot of it — pressurized air.

If the pressure in the chamber is too high and the pellet hasn’t started moving, either because of its size, weight or both, the piston can rebound off the compressed air cushion and travel backwards a few hundredths of an inch before the pellet starts to move. Heavier pellets will resist moving longer than lighter pellets — I hope that’s obvious.

By adding a lot more weight to the piston, it can resist rebounding to a greater degree (because of its greater inertia). Heavier pistons usually do better with heavier pellets. And top hats are one way to make pistons heavier. That’s why I said what I did.

Whew!
That was a quick and dirty look at the spring-piston powerplant and some of its subtleties. Don’t think this makes you an expert — there’s a whole world of things like this that I haven’t addressed.

BSA Supersport SE: Part 1

Tom Gaylord, a.k.a. B.B. Pelletier

BSA Supersport SE
BSA Supersport SE

Today, we’ll begin looking at a .22-caliber BSA Supersport SE. This is a conventional breakbarrel spring piston air rifle in a beech stock. It’s been some time since I’ve tested a conventional new spring rifle like this.

The serial number of the rifle I’m testing is SSE22-770789-13. The metal finish is unpolished but probably tumble-finished, giving all the parts a matte sheen. The only plastic parts you can see on the outside are both sights, the safety lever and the triggerblade. They blend into the overall matte black finish very well.

The stock is shaped well and has 4 panels of pressed checkering — one on either side of the forearm and one on either side of the pistol grip. The BSA stacked rifles logo (called piled rifles in the UK, and the BSA logo is called the Pylarm logo) is pressed into the base of the pistol grip. The wood is finished smoothly, and the only rough area is the point where the black rubber buttpad meets the wood. That transition isn’t smooth, and there’s glue around the joint.

BSA Supersport SE butt
The joint at the buttpad is a little rough and has dried glue.

The barrel comes very far back when the rifle’s cocked, making this a long-stroke piston. The cocking linkage is in 2 pieces that are jointed to keep the cocking slot in the stock as short as possible, which reduces the feeling of vibration. BSA says that the action is internally weighted to deliver top performance. I’m thinking they mean that there’s a weighted top hat inside the piston, or the piston itself is heavy. Either way, the rifle should shoot medium and heavyweight pellets better than lightweight pellets.

BSA Supersport SE air rifle
The barrel comes way back when the rifle’s cocked. That means the piston stroke is long.

The rifle is supposed to weigh 6.6 lbs., according to BSA information. The rifle I’m testing weighs 7 lbs. on the nose. The difference is attributable to the density of the wood in the stock.

BSA advertises the muzzle velocity at 730 f.p.s. That would be with a lightweight pellet, but I’m hoping it’s a light lead pellet. If so, that’s a good velocity for a .22 spring rifle — not too fast, yet plenty of power. We’ll find out in the velocity test.

The trigger is adjustable via an Allen wrench. The adjustment works on the second stage to lighten it or make it heavier. The safety is manual, which I must applaud. Only the shooter should be in control of the gun — never the design!

The sights are fiberoptic, front and rear. The rear sight adjusts in both directions, so I’ll start the accuracy testing using the open sights.

BSA Supersport SE front sight
Front sight is fiberoptic.

BSA Supersport SE rear sight
Rear sight is fiberoptic and adjusts in both directions.

There’s an 11mm dovetail groove machined into the top of the spring tube, but BSA has long been noted for having its grooves set at the widest end of the size spectrum. For newer readers, 11mm is a nominal size for airgun dovetails. They actually range from 9.5mm out to almost 14mm, and BSA has always had the widest set. But it looks like the grooves are now 11mm apart.

I’m very pleased to see a deep, wide vertical scope stop hole in the middle of the dovetails at the rear of the spring tube. This provides a solid anchor point for a vertical scope stop that most of the conventional 11mm scope rings have.

BSA Supersport SE scope stop hole
This deep, wide hole in the spring tube is for a vertical scope stop.

Solid firing cycle
I couldn’t resist shooting the rifle a couple times to check the trigger and the firing cycle. The trigger is definitely 2-stage, with some creep in stage 2. I’ll work on that for next time. The firing cycle is quite smooth. It’s got a hint of spring buzz, but only a hint. The shot feels solid and there is no hurtful vibration at all. This is a very pleasant spring rifle to shoot!

I would add that, when I cocked the rifle, the stroke felt to smooth that I almost thought it had a gas spring. Ten years ago, I would have said this rifle has been tuned. It feels that smooth. The cocking effort is heavier — going up around 40 lbs., as a guess. In recent years, I’ve seen a number of breakbarrel air rifles that cocked as smooth as this one, so what I believe is happening is the manufacturers are paying more attention to the internal tolerances. The result is that the buyer gets a smoother air rifle; and at the price for which this one retails, that’s quite a bargain. Five years ago, you got something much harsher for the same $250.

I have owned and tested BSA Supersport rifles in the past. In fact, in the 1990s they were a huge seller here in the U.S. They are no-frills rifles that offered good performance and accuracy at a good price. Let’s hope BSA has continued that tradition in this latest offering.

BSA Meteor: Part 8

by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1
Part 2
Part 3
Part 4
Part 5
Part 6
Part 7

BSA Super Meteor
My rifle is actually a BSA Super Meteor.

Today, you’ll see how I fixed the bad muzzle crown on the BSA Super Meteor, and then we’ll see if that had any effect on the rifle’s accuracy. You might want to read Part 7, again, just to remind yourself of what I faced.

The BSA project has been just that — a project from the start. All I wanted to do was test another vintage spring-piston air rifle for you and report the results, but this particular air rifle has challenged me at every turn. From the time I bought it at the Roanoke airgun show last September, it’s been nothing but a prolonged learning scenario. I won’t bore you by recapping all that’s happened; but if you want to find out, read Parts 1 through 7.

At the end of Part 7, I showed you a nasty muzzle crown, which I surmised was the reason that all the pellets were leaving the barrel with a yaw to their axis. They weren’t tumbling, because every one of them struck the target paper in exactly the same orientation. They were yawing, or traveling forward while pointing off to one side. Because the barrel is rifled, they were spinning on their long axis, but that axis didn’t happen to coincide with their flight path.

Meteor crown
The BSA Meteor crown has some serious nicks in it. The dark spot at 10 o’clock is the deepest. Compressed air could escape through this channel before any other part of the pellet leaves the bore, and the jet of air could push the pellet over on its side.

The solution was to crown the bore; but as you can see in the picture, the Meteor’s muzzle is counterbored by more than an inch. In other words, it isn’t where it appears to be from the side. It’s deep inside the barrel, where the theory says it shouldn’t get damaged as easily. Only this one was — perhaps from over-zealous cleaning through the muzzle. Who knows? The point is that it had to be fixed.

My shooting buddy Otho suggested a piloted counterbore to face off the crown true and square to the axis of the bore. And he volunteered to make the pilot, so I slugged the bore for him and found it was a diameter of 0.176 inches. That seemed odd to him because it’s larger than the bore of a .17-caliber rimfire bullet that’s about 0.172-inches. But that’s the difference between .17 caliber and .177 caliber — which is important for airgunners and firearms shooters to know. The pilot he made measures 0.1745 inches and fits the Meteor’s muzzle comfortably.

Meteor crown end mill
Otho made the pilot for this counterbore.

The counterbore chucked up perfectly in my portable electric drill. I allowed extra length for the bore to go down into the barrel and touch the muzzle without the drill chuck touching the barrel.

Meteor crown end mill in drill
The counterbore is chucked in the drill and set to run true. It sticks out far enough to cut the crown without the drill chuck touching the barrel.

Plugging the barrel
Before starting the work, I pushed 3 fat pellets into the breech and then pushed them with a cleaning rod to within 2 inches of the true muzzle. These will keep the metal chips from dropping down the bore.

I oiled the counterbore and pilot with a good grade of light machine oil before inserting it into the muzzle of the gun. The drill was set on a slow speed, but I can also control the speed by how hard I squeeze the trigger. I wanted a slow steady turn without putting much pressure on the drill. The counterbore is sharp enough to cut the soft barrel metal without a lot of encouragement.

Meteor crowning the muzzle
The drill is set to run slow, and I’m also slowing it more with the trigger. You don’t need speed for a cut like this.

After about 10 seconds of cutting, I removed the counterbore and cleaned the new crown with a cotton swab. There was a band of bright metal around the muzzle where the counterbore had cut. Upon close examination, I could still see gouges in the bright band. The gouges were deeper than the first cut.

Meteor crowning first cut
The new crown is bright after the first cut, but there are still gouges that need to come out.

I cleaned the counterbore with a swab and oiled it again. Then, I made a second cut on the crown. This time, I felt the drill pulse as the cutter removed the uneven metal. It became smooth, and I knew the cut was finished. When I cleaned and inspected the new crown this time, it appeared smooth and even. The job was done.

Meteor crown complete
I apologize for the blurriness of this picture. Focusing on the crown is very difficult when I’m also trying to light it from the same axis as the lens is pointing. The lens is about one inch from the end of the barrel, and this was the best picture I got. There are still some faint marks on the crown. After examination with a loupe, I didn’t think they would be a problem.

At this point, I felt the crown was as clean as I could get it. And there was a simple way to see if this had made a difference. I drove the pellets in the bore out the muzzle and a few steel chips came with them. Next, I shot two RWS Hobby pellets offhand from 12 feet. If the crown was good, they would cut the paper perfectly instead of hitting sideways. And that’s what happened.

So, I backed up to 8 yards and shot 2 more shots from an improvised rest. These 2 pellets landed very close to each other and also showed no signs of tipping. I felt the job was done.

Meteor crown proof target
The two lower shots were from 12 feet. They confirmed the pellets were hitting the paper straight-on. The two upper shots were from an improvised rest at about 8 yards. They told me the crown is probably working.

Now for the test!
The test is a rerun of the Part 7 accuracy test. I used every pellet from the last accuracy test and shot at the same 10 meters.

Pellets:
Eley Wasp
Crosman Premier lite
Air Arms Falcon
RWS Hobby

Meteor crown proof Wasp target
Ten Eley Wasps went into 2.256 inches at 10 meters.

Meteor crown proof Premier lite target
Ten Premier lites went into 1.522 inches.

Meteor crown proof Falcon target
Ten Air Arms Falcons went into 1.941 inches.

Meteor crown proof Hobby target
Ten RWS Hobbys went into 1.361 inches.

Conclusions
If you compare these targets to those in Part 7, one thing jumps out at you. None of these pellets tipped when they went through the paper. So, crowning seems to have solved that problem!

But the accuracy seems no better. The Hobbys did group better in this test, but the Falcons grouped worse. With groups this large at 10 meters, I’m not willing to say anything has improved. I’ve had cheap Chinese air rifles group better than this.

I have one trick left up my sleeve. I’ve noticed that the Meteor rear sight seems hinky and difficult to adjust, and I suspect it jumps around as I shoot. It’s not loose to the touch, but I don’t trust it to hold zero.

I’ll do one more test of this rifle with either a dot sight or with the See All Open Sight if I can get it mounted to the Meteor. If that doesn’t work, I’ll probably abandon this air rifle as a bad investment.

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