Let’s make lemonade

by Tom Gaylord
Writing as B.B. Pelletier

History of airguns

This report covers:

  • Lemons
  • The bigger picture
  • Whodunit?
  • So what?
  • They got better
  • The point?
  • Summary

I was all set to begin telling you about my Beeman 400/Diana 75 today. Yes — my rifle is a Beeman 400. I’ve had people tell me Beeman didn’t sell a 400, but I’ve got one to show you. However — not today.

There is one part of the Diana 75 sidelever recoilless air rifle that I had to discuss with you first and, as I thought about it, this one component is more important than the entire target rifle. So today I tell all of you how to make lemonade. Some of you will make it, some will even set up lemonade stands while others will continue to curse the darkness.


The world of airguns is replete with lemons. In 2018 I told you the story of a Benjamin 700 that was practically forced upon me at the 2018 Texas Airgun Show by one of our regular readers — I forget who. The price of $95 was certainly good. But then I had to get it fixed and, by the time that was over, I had three times the money invested in the airgun. By the way, that BB repeater now holds air indefinitely and is looking for a new home.

The Schimel was a new CO2 pistol in 1950. It was unique, in that it was a CO2-powered .22 pistol that shot pellets at 550 f.p.s.! However, unlike Crosman who had been building CO2 guns for decades by 1950, the Schimel was made with high-tech all-new materials. Unfortunately many of them did not withstand the test of time. The metal parts welded to one another through electrolysis, the o-ring seals absorbed gas and locked the gun up tight for hours after the cartridge was empty, the paint flaked off all over the gun and the plastic grip scales shrunk and warped over time.

The Schimel looks like a P08 German Luger and my wife, Edith, who saw the air pistol first, always called my 9mm 1914 Erfurt Luger a Schimel. 

The bigger picture

Those guns and others like them were unsatisfactory, but they were nothing compared to the tens of thousands of failures that were foisted upon the airgunning public in the 1960s and ’70s. Companies with solid reputations that we still trust today sold tens (hundreds?) of thousands of premium airguns to unsuspecting customers who only found their Achilles heel a decade later. Their piston seals were made of the wrong synthetic material! That material worked well when it was new and fresh but it hardened in the air and slowly turned into a dark yellowish waxy substance that fell apart in small chunks. I have found bits of brownish-yellow wax in the barrels of dozens of these airguns. Not one of them escaped this fate and in 2021 there isn’t one of them that still has its original seals.

124 perished seals
This FWB 124 pistol seal was white-ish when new. This brand new seal has never been in an airgun. Years of exposure to the atmosphere have turned it brown and dried it out. It does the same thing inside an air rifle.

I wrote about one of these airguns in the 15-part series, A shrine built for a Feinwerkbau 124, back in 2010 and 2011. Yes, the legendary Feinwerkbau put the new bound-to-fail synthetic seals on their iconic 124 (and 121, 125 and 127). That’s tens of thousands of airguns, right there! And yes, I did write a 15-part report about the 124. I also wrote a great many more reports about that model over the years. Many of them have been about replacing the original seals with ones made from modern materials. I have probably resealed 12 to 15 model 124s in my time.

Okay, get angry! Why would such a prestigious airgun manufacturer put something that was bound to fail in their finest products. Let’s see. Perhaps they didn’t know?

Why would Coca-Cola change the formula that made them the world’s leading soft drink producer? Why would NASA skip some of the testing for the Hubble Space Telescope before launching it into orbit? I could go on but the answer is always the same — they didn’t know.


Now we come to the part of today’s report that explains why I didn’t start presenting the Beeman 400/Diana 75 today. You see — Diana also used this new synthetic material in their piston seals. That makes the following models subject to early failure.

Diana 5 pistol
Diana 6 target pistol
Diana 10 target pistol
Diana 60 target rifle
Diana 65 target rifle
Diana 66 target rifle
Diana model 70 rifle
Diana model 72 target rifle
Diana model 75 target rifle

And the companies that sold these airguns under other names, like Beeman, sold them under different model numbers, as well. But wait — there’s more!

Walther also used this synthetic material in their airguns made during this same timeframe. That made the following models that are prone to early failure.

Walther model 55 target rifle
Walther LGV target rifle
Walther LGR target rifle

I have resealed two LGVs for this problem, and I paid someone else to reseal one because he wouldn’t sell me the parts. I have an LGR that was also resealed.

So what?

BB, you’re painting a dismal picture here! This is why I won’t buy a used airgun.

Well, you do what you think is best, but I am telling you that this has opened up a grand world of opportunity to those who can work with it. You can either complain that the lower 40 acres on your Titusville, Pennsylvania, farm is all full of black sticky muck that clogs your plow or you can arrange to sink an oil well and become a millionaire!

Guys, what BB is telling you is there is a huge stock of wonderful airguns rotting away in closets because they suddenly stopped shooting when the barrel filled up with the brown waxy stuff. They would have been thrown away years ago but the supply of round tuits was temporarily exhausted. It’s hard to hold an FWB 124 or a Diana 72 in your hands and not realize what a diamond it is!

They got better

All those prestigious companies who were bamboozled by the early synthetics (remember, Benjamin Braddock — plastic is the future! {from The Graduate}) learned their lesson and made their seals out of new material that lasts virtually forever. They each went a different way but all of them figured it out, just like General Motors figured out that timing belt gears should not be made out of Nylon!

While “they” were figuring it out, the aftermarket guys also got with the program and better synthetic piston seals began showing up worldwide. So today a 124 that’s no longer being used is a loving puppy that needs to be adopted. I once bought one for $35 — from an airgun dealer! I bought a nice one for $200 a few years back — from a gun dealer who took it on a trade in for a “real” gun. That one I still have.

I even bought a 124 complete action in a deluxe stock at a gun show for $50 a few years ago. But I sold that one to another airgunner who said he had a barrel.

The point?

If you haven’t gotten it by now, bless your heart! What I’m saying is that there are thousands of worthy airguns laying around that are simply in need of a new piston seal. These aren’t cheapies, either. These are good airguns. Just look at the list up above again. But their owners don’t appreciate them anymore.

I bet if there was a pristine 1957 Chevy Bel Air parked out in the street and the For Sale sign said its original 283 original engine was’t running, people would find a way to do something about it! BB Pelletier just told you that there are thousands of them and you just have to look for them.

Look in odd places. Don’t look in the car trader magazines for ’57 Chevys. Everybody looks there. Look behind the body shops and repair shops around town. That’s where the mechanic parked them, waiting for the owner to pay his bill. And he never came back. Sure there is no title, but we are talking about airguns — not cars! Don’t need no title for an FWB 124 or an RWS 75.

Read the ‘spensive Gun Broker ads that say “I don’t know how well this RWS Diana 75 rifle works because I don’t have any pellets to shoot in it.” Sure — we all believe that. So you contact that guy and tell him that a piston seal replacement for a Diana 75 will cost you at least $350 — $250 for the work and parts and $100 for shipping both ways. Tell him you’ll give him $250 for his $575 air rifle, plus $50 to ship it and then, if it does have the bad piston seal problem, you do have to pay the rest to get it fixed. And you come out about even. But if it doesn’t… oh, happy day!

Or, you can fix it yourself. Or, you will luck out and discover that it works fine. Or, the seller will discover that he actually does have some .177 pellets and the gun does, in fact, work. Then you ask him what pellets he has and what velocity the rifle shoots them at and he tells you that he doesn’t have a chronograph. And on and on…


Now I’ve told you all that is behind the piston seals of a Beeman 400/Diana 75. That means that on Monday you can light just one little candle and stop cursing the darkness.

Umarex Fusion 2 CO2 rifle: Part 3

by Tom Gaylord
Writing as B.B. Pelletier

Fusion 2
Umarex Fusion 2 CO2 repeater.

Part 1
Part 2

This report covers:

  • A dime spacer
  • It worked!
  • Velocity
  • No feeding problems
  • Trigger pull
  • One final tip
  • Where we stand
  • Summary

Today we look at velocity of the Umarex Fusion 2 repeating air rifle again. After Part 2 I considered all the remarks carefully. I wanted to test the rifle’s accuracy but not before knowing how many shots I could count on.

A dime spacer

Reader EricfromSC said he used a dime as a spacer between the two CO2 cartridges and it worked. He also mentioned that he had the same magazine feeding issues I encountered and that by holding the rifle level when working the bolt they were resolved. When I test velocity I often cock the rifle with the muzzle up, so this time I was careful to hold it level.

I first dropped about 10 drops of automatic transmission stop leak into the CO2 tube before dropping the first CO2 cartridge in. Then I dropped in a Crosman CO2 cartridge. Since they were the only brand that actually worked in Part 2 I felt I needed to stay with them.

The I dropped in the first cartridge, followed by a dime. I wondered whether the dime would tilt sideways in the tube and mess things up, but it fit like it was made for it.

Fusion 2 dime
You are looking halfway down into the Fusion’s CO2 tube. The dime is resting on the wide end of the first CO2 cartridge. The fit is perfect.

For those in other countries who don’t have American dime coins, I used a new coin. The diameter is 17.91mm and the thickness is 1.35mm. The dime fits loosely enough that sticking won’t be a problem.

It worked!

I’m pleased to say the dime trick worked and both CO2 cartridges were pierced quite well. Look at the holes.

Fusion 2 cartridges
This time both CO2 cartridges were pierced well. The bottom one that had all the trouble before is on the left.


I decided to only shoot the JSB Exact RS pellet, as it has no feeding issues last time. The first 9 shots gave an average 640 f.p.s. The low was 634 and the high was 652, so a spread of 18 f.p.s.

The second 9 shots averaged 642 f.p.s. The low was 633 and the high was 651, so  another spread of 18 f.p.s.

The third 9 shots averaged 623 f.p.s. The low was 605 and the high was 641 f.p.s. So the spread this time was 36 f.p.s.

The fourth 9 shots averaged 553 f.p.s. The low was 506 and the high was 590 f.p.s.

I will show you the fifth string.


I ended the test at this point to keep from sticking a pellet in the barrel. Without a doubt the Fusion 2 uses a LOT of CO2!

No feeding problems

Once I held the rifle level as EricfromSC suggested the feeding was perfect. But I will say that every time the bolt passes through the magazine you can see the mag move a little. So watch this!

Trigger pull

I didn’t give you the trigger pull in Part 2. The trigger is single-stage with a long smooth pull that maxed at between 3 lbs. 3 oz. and 3 lbs. 8 oz. The average was 3 lbs. 6 oz.

One final tip

It occurred to me that since I had removed the CO2 adaptor tube to try the 88-gram cartridge, it was now coming out of the rifle every time I installed new cartridges. Looking at the manual I see that it’s not supposed to do that. So here is my tip. First, screw the adaptor into the rifle as far as you can, then load the two cartridges with the dime between. When you screw the knurled end cap down, leave the relief valve open so you can hear when the lower cartridge is pierced. The knurled end cap will allow you to screw the adaptor down as far into the rifle as it will go. When the hissing starts, screw the relief valve down as far as it will go. The hissing stops right away but keep turning the valve until it stops to pierce the top cartridge fully. I conducted several experiments to determine this was the most reliable way to pierce both cartridges! I do not care for this design! 

Where we stand

Now that the rifle is working and I know its quirks I’m ready to move on to accuracy testing. I hasve read so many good things about the accuracy that I’m looking forward to it.

I would like to thank EricfromSC for his comments to Part 2. Without them I don’t think I could do an accuracy test on this rifle.


I have this to say about the Fusion 2. It has some shortcomings that I was able to overcome with help. I wish the magazine was more positive and why can’t I still get the 88-gram CO2 cartridge to pierce. Those things need to be addressed. But if you own one, I hope today’s report helps you.

Endosnake borescope

by Tom Gaylord
Writing as B.B. Pelletier

The Endosnake is an affordible endoscope/borescope that works with a smartphone or computer. The camera has mini LEDs to illuminate what’s in front of it.

This report covers:

  • A job worth doing…
  • First use
  • Videos not necessary
  • Resolution
  • Summary

For years I have wanted a borescope so I could look inside my barrels. Twenty years ago they were priced in the thousands and out of my reach. Ten years ago they dropped into the hundreds and were still pricy. But they were not optimized for airguns. They were mostly sized for .22 barrels, as though AR-15 owners were the target market. Again, I had no interest.

Then about two months ago I started getting emails about a product called the Endosnake. It was selling for $50 and I needed a wifi kit to connect it to my iPhone. I got the one that’s 2 meters long. The camera is 3.9mm in diameter and when I asked the Endosnake people whether it would fit into a .177 caliber airgun bore they said they didn’t know. Well, I know now and it does!

A job worth doing…

… is worth doing poorly. A pastor of mine used to say that. In other words, get on with it. Don’t wait until it’s perfect! In the interest of sharing the Endosnake with you today that’s just what I have done. I have two videos that are both silent. They will show you what I have seen so far and perhaps give you some ideas of how this tool might be used.

First use

I will call the first video the first time I used the Endosnake, but the truth is, it took me many tries and three days of playing with it to get what I’m about to show you. Hopefully I will get better with practice

A reader remarked that he would like to see the inside of the Slavia 618 barrel. So I photographed it for you. I also photographed my keyboard before putting the camera inside the bore. The film resolution is low so the image isn’t sharp, but it does show all the detail. Of course if you have never looked through a borescope the 360-degree image may be difficult to resolve the first time you see it.

The second video is looking through the barrel of a .177 caliber Crosman Mark II pistol. It’s a BB pistol, yet you will clearly see some shallow rifling. I go from the muzzle to the breech and out into the loading trough, and then back through the barrel again. In the breech as we come back I pause and you can see two dark spots in the circle of light. They are the gas transfer ports in the breech. Let’s look.

Videos not necessary

When the Endosnake is turned on you don’t need to record what’s happening. You can see it on your smart phone as the camera moves. Only record it if you want to. You can also take still photos if you prefer.


The software shows a wide range of possible image resolutions but every time I tried to change it the software said it failed. So I left it where it was, which was very low res. Maybe when I learn the software more I will discover how to change it.

The Endosnake works with Windows 10, Android phones, Macs and iPhones. There are several photo softwares that it can work with. But the support for the product is poor, in my opinion. The “manual” is almost non-existent and you have to do a lot of searching around their website to figure things out — or at least I did.

Besides the 3.9mm Viper outfit I bought there are also cameras for 5.5mm, 7mm 8mm and 14mm. And they offer package deals with multiple cameras.

I plan to use this in future articles as well as around the house. Ever wonder what’s stuck in the garbage disposer? What other uses can you think of?


I have used borescopes for the past 50 years — starting with those big one for the 105mm cannon on the M61A1 tank. This Endoscope is quite remarkable, especially considering the low cost.

Slavia 618 breakbarrel air rifle: Part 1

by Tom Gaylord
Writing as B.B. Pelletier

Slavia 618
Slavia 618.

History of airguns

This report covers:

  • History
  • Research
  • Model variations
  • What is the Slavia 618?
  • Comparisons
  • Stock
  • Summary

Some of you may have been hoping for Part 2 of the Beeman R10 rifle report today. Well, Part 2 will be the strip-down and installation of the Vortek tuning kit, and I need a couple days to do the work and take the pictures, as well as the writing. So today I’m starting my report on the Slavia 618 breakbarrel pellet rifle.


Guess what? Almost nobody knows the history of this air rifle. It has a lot of fans, but nobody seems to know much about it.

The Blue Book of Airguns says it was made in the 1970s — period. But they say the same thing about the Slavia 622. Well, I received one of those as a gift in about 1961 or ’62, so that’s obviously not right.

My rifle from the early 1960s was labeled PIC, for Precise Imports Company. They were one of the U.S. importers of Slavia airguns. Considering when I got mine I believe the 618 and 622 had to have been made in the 1950s. The 1970s as an ending date I don’t dispute.

No doubt there is someone who lives close to the Czech Republic that was formerly Czechoslovakia where the arsenal that made the air rifle is located. It was made at Ceska zbrojovka in Brno. I apologize for not having the correct diacritical glyphs on the cyrillic letters in the names.


I researched a lot of expired auctions to gather any information I could find on this model. I see that around 2010 these air rifles were bringing $20-35. Today most hover at the $75-100 range, with shipping raising that even higher.

Model variations

I bought one 618 off Ebay that was supposed to be in good working order. It is, except the rear sight is bent to one side from what looks like a fall. I was going to leave it alone and just test the rifle, but then a second one popped up for less money. This one was advertised as complete but needing seals. That was also an accurate description, though it needs a little more than just seals. It feels like it is gunked up inside and at least needs a good cleaning. We’ll know more when I open it up.

I will say that the both the wood and metal finishes are poor on both my rifles. The shellac is apparently not long-lasting and the metal rusts easily. Many of the 618s look like this.

I can test the first rifle for velocity, at least. I’m expecting it to be in the low 300s with lightweight pellets. I found velocities from 312 f.p.s. for a tired one shooting Crosman Premier Light pellets to 390 for the same rifle after a rebuild.

What is the Slavia 618?

The Slavia 618 is a small youth-sized breakbarrel air rifle. Several weeks ago when I tested the Diana 23, a similar youth-sized air rifle, a couple readers mentioned how much they enjoy their 618s. That’s why I got these two rifles to test, study and rebuild. I have been hearing about the 618 from readers for many years and decided it was time I investigated for myself. Side-by-side the Diana 23 and the Slavia 618 are very similar. The Diana is a little longer overall, at 35-7/8-inches versus 35-1/4-inches for the 618.

As far as I can tell, the 618 only came in .177 caliber. It was the 622 that was a .22 (only). One reference mentioned that some 618s were rifled and others were not, but I can’t really prove that. Both of mine appear to be rifled.

One of my 618s weighs 3 lbs. 6 oz. Because of the wood stock and one other difference I will tell you about, there will be small weight differences, but all 618s are lightweight.

When I looked at both my rifles I discovered several difference between them. These are differences that would come over a longer production cycle, which is why I think the Blue Book dates of the 1970s fall short. I am assuming that over time the design of a product will be changed to make it less costly to produce. With that assumption in mind, I have labeled one of my rifles as older than the other. Let me explain why.


The rifle I’m calling older has a thicker barrel. It measures 0.502-inches or 12.75mm in diameter at the muzzle. The newer rifle measures 0.468-inches or 11.89mm at the same place. The front sight on the older rifle is a blade sitting in a dovetail. The front sight on the newer rifle is a plain round pin. Since dovetails are more difficult to cut, I think that first one has to be older.

Slavia 618 nuzzles
The muzzle on the right is on what I am calling the older rifle. It’s larger than the muzzle on the left.

Slavia 618 older sight
The front sight on the older rifle is a raised post that’s dovetailed into the barrel.

Slavia 618 newer sight
The front sight on the newer rifle is just a plain round post.

The rear sights on both rifles appear identical, but the sight on the older rifle is spot-welded in two places to the dovetail that slots into the barrel and on the newer rifle it’s welded to the dovetail in just one place. The sight with the single weld is also the one that’s bent, and, looking down from the top it appears the weld may have weakened when it allowed the bend. I plan to try to tap it back straight, but I won’t be surprised if that weld shears off in the process. That sight leaf is also bent upward, so some of the elevation adjustment has been lost.

Slavia 618 bent sight
The rear sight on the newer rifle has a single weld and has been bent to the left.

Slavia 618 straight sight
The older rifle rear sight is straight and has two welds.

Both of my rifles have a leather breech seal, which leads me to believe they both have leather piston seals, as well. In my research I discovered that the 618 also came with an o-ring breech seal and a synthetic piston seal. I bought a synthetic breech and piston seal while awaiting the arrival of both rifles, but now I don’t know that it can be used in either one. Fortunately leather seals should be easy to fabricate.

I also bought two new mainsprings that both rifles probably need. We will see when we open them up.

Neither of my two rifles have a serial number. Some 618s do and others don’t On the 618s that have them, the serial number is stamped into the flat left side of the base block that holds the barrel. I saw serial numbers as high as 150,000+ when I researched the rifle. The serial number may have been required for certain countries to import the rifle, or CZ may have started putting numbers on all its air rifles at some point. Either way it does suggest, along with the leather seals, that my two rifles are older examples.

I saw one other interesting thing in my research. Many of the 618s I saw had two screws at the pivot joint. One was the pivot bolt and the other was a locking screw on the main bolt’s periphery. Both of my rifles have just a single pivot bolt. The other side of the bolt screws into a threaded nut that has two spanner holes for anchoring it when disassembling the rifle.

Slavia 618 two base blocks
As you can see, there is no serial number on either base block. And the pivot bolts have no locking screw. The rear sight on the upper rifle is bent up.

Both my rifles have the model name, number and country of origin stamped into the top rear of the spring tube. These markings run perpendicular to the axis of the spring tube. There are other 618s that have the same markings running along the spring tube’s axis, and in several places I found references to that variation being older.

Slavia 618 writing
Both my rifles have writing that’s perpendicular to the axis of the spring tube.

Both spring tubes on my rifles are plain, but I did find a 618 on the internet that had a short set of grooves at the rear of the tube. They were less than two inches long. The person doing the review thought they were there for mounting a scope but I’m pretty sure they are there for a peep sight.

The compression chamber is made by swaging a solid steel block into the end of a hollow steel tube. The transfer port has been drilled through this block, so once it’s held in by the swages, a spring tube is born.


All the 618s I found, including the two I own, have a one-piece beechwood stock with finger grooves on both sides of the forearm. I did see one 618 with a custom-made walnut stock and of course our own reader, Vana, made a stock for his 618 out of firewood that he described in a 6-part report.

The buttstock has fine ridges over the central half of the wooden buttplate. The pull is 13-1/2-inches.


What we have with these two Slavia 618s is the potential for a lot of fun. You readers seem to have created another fan!

AirForce Edge 10-meter target rifle: Part 3

by Tom Gaylord
Writing as B.B. Pelletier

AirForce Edge.

Part 1
Part 2
Part 3
Part 4
Part 5
AirForce Edge 10-meter target rifle: Part 1
AirForce Edge 10-meter target rifle: Part 2

A history of airguns

This report covers:

  • Accuracy day
  • Dropped a shot
  • What was happening?
  • The problem
  • Went to AirForce
  • Adjusting an Edge top hat
  • Purpose of the o-rings
  • Adjusted the top hat
  • RWS Basic
  • H&N Finale Match Light
  • RWS R10 Match Pistol
  • Sig Match Ballistic Alloy
  • Shot count
  • Off the regulator
  • One last thing
  • Summary

Oh, boy! Every once in awhile something big happens with this blog, and today is a report on such a time. This is about the AirForce Edge.

To tell the complete story I first have to tell you some bad news. I want you to read it without getting angry, because if it hadn’t happened as it did I would not be able to tell you the extraordinary news I’m about to tell you.

Accuracy day

This report was supposed to be the first test for accuracy. I knew there were going to be several accuracy tests, but this would be the first one. Except the rifle didn’t cooperate.

I spent a hour sighting in and then shooting the first three groups. I have a lot to tell you about adjusting the rear sight, but that will wait until another time, because what I have for you today is much more important.

Dropped a shot

I was shooting RWS R10 Match Pistol pellets that showed every possibility of grouping extremely well — UNTIL! Until I heard a shot go out that was audibly much slower than the rest. When I looked through the spotting scope I saw that pellet had dropped about a half-inch. A half-inch for a 10-meter target rifle shooting at 10 meters is like trying to fly to Buffalo and landing in Cleveland, instead! I was shocked!

I thought the only thing to do was shoot another group and see what happened. The first two shots went through the same hole, then shot three landed a half-inch below them and shot four was another half-inch below that. Test over!

What was happening?

I took the rifle back to my office and examined it, and the o-rings that both Chris USA and GunFun1 commented on in Part 2 were even more off-center than before. Okay — BB was wrong when he told Chris USA there was no problem with those rings. Apparently there was a problem. But it wasn’t with the rings themselves. Wait for it.

Edge top hat
This is the photo that several readers didn’t like. They felt that the o-rings sitting askew like this was messing with the rifle’s output. There was a problem, but this wasn’t exactly it. Still, these o-rings don’t have to look like this.

The problem

We haven’t gotten to the problem yet! But I thought I would remove those two o-rings and replace them with something that fits the valve stem better, and do you know what I discovered? The two Allen screws that anchor the top hat to the valve stem were not tight! Every time I closed the bolt, it rotated the top hat by a small amount — or at least it had the potential to! That was the problem!

Once the top hat was off the valve stem, I removed the two o-rings AirForce had installed and replaced them with two metric 007 Buna o-rings. But you need to understand that those o-rings have very little to do with the velocity of the airgun! The distance that the top hat travels has a lot to do with it! And there is more. I have more to tell you about what the o-rings do in a little bit, but right now let’s move on.

Went to AirForce

I took the AirForce o-rings and one of my 007 o-rings to AirForce to speak with Ton Jones who had personally set this rifle up for me. I told him the Allen screws that lock the top hat in place had not been tightened and he was surprised — at first. Then he remembered that he had set up this valve and reservoir for me and gave it directly to me, instead of sending it on to the next AirForce station. Ton had snugged both screws down but not tightened them. At the next station another worker unscrews each Allen screw one at a time and dips it into blue Locktite! Then the worker tightens the locking screws tight so the top hat remains were it was adjusted by either Ton or one other person who adjusts each Edge over a chronograph. 

I showed Ton the Part 2 photo of the top hat with the wonky o-rings (shown above) that you readers took exception to. He said yes, the rings askew like that is a problem, but not a big one because the top hat isn’t supposed to even touch the top o-ring when it is set correctly.  HUH?

Adjusting an Edge top hat

What I am about to tell you has only come to light in the past month. Until right now AirForce had a different procedure and specification for adjusting the Edge top hat. But Ton Jones took an Edge to his wife’s parents’ home in Slovakia on vacation last year and he got it working very well. When he told the owner of AirForce about his experience he was asked to determine exactly what he had done and write it all down for a new specification. That work took him many weeks, intermingled with his other duties, but he has now codified the top hat adjustment procedure for everyone.

To adjust the Edge top hat, first make sure both of the locking screws on its periphery are loose and the top hat turns freely on the valve stem. Then cock the rifle and watch the top hat as the bolt comes back to its rearward position. When the top hat just turns just a little as the bolt is closed, it is adjusted correctly. With the o-rings AirForce was putting on the valve stem there will be a clearance of about one o-ring’s width above the top o-ring and the bottom of the top hat when it is set properly. With the fatter o-rings (the metric 007 rings) that I am using, there is only a thin sliver of clearance between the top of the o-rings and the bottom of the top hat. Each rifle is different though and must be adjusted by hand this way.

Purpose of the o-rings

The o-rings are there to control the amount of distance the valve opens — BUT by the time the top hat starts to compress them, the pellet is almost out of the barrel. They don’t really control the velocity of the pellet; they control the amount of air that’s wasted after the pellet leaves the barrel. The valve return spring tension, the length of the valve stem travel (controlled by the top hat) and the regulator pressure setting control the pellet’s velocity. And each airgun is different.

I have prepared a short video to show you how the top hat is adjusted.

Adjusted the top hat

After I filmed that video I adjusted the top hat as shown and locked down the two locking screws. I am now ready to test the Edge velocity again — this time knowing the top hat will not move.

As I shoot I’m not allowing any particular amount of time between shots. I watched the clock and it seemed as though it took me 20 seconds to do everything between each shot. So that is the interval for the shots that follow.

RWS Basic

Once again I used the RWS Basic pellet as my principal test pellet. In the first string after filling the rifle to 3.000 psi Basics averaged 534 f.p.s. How interesting that number is so close to what they did the last time. This time all pellets were seated thumb deep. The low was 518 and the high was 545 f.p.s., so the spread was 27 f.p.s.

H&N Finale Match Light

Next to be tested were H&N Finale Match Light pellets. They averaged 523 f.p.s. with a low of 510 and a high of 540 f.p.s. The spread was 30 f.p.s.

RWS R10 Match Pistol

The third pellet I tested was the RWS R10 Match Pistol pellet. Ten of them averaged 554 f.p.s. The low was 539 and the high was 567 f.p.s. So the spread was 28 f.p.s.

While shooting this string I got curious if a longer wait between shots would tighten the velocity spread. So for the first 5 shots in the next string of the same R10 Match Pistol pellets I waited 60 seconds between each shot, and for the last 5 shots I waited my normal interval, which is about 20 seconds.


Then I waited the normal interval between shots, which is about 20 seconds.


I seems like shooting at the normal interval of about 20 seconds is more consistent than waiting a minute between shots

Sig Match Ballistic Alloy

The last pellet I tested was the Sig Match Ballistic Alloy wadcutter. They averaged 634 f.p.s. with a low of 621 and a high of 642 f.p.s. That’s a difference of 21 f.p.s.

Shot count

Now the real test begins. I will shoot RWS Basics for the remainder of this test. How many shots will Ton Jones’ method of adjusting the top hat produce? I shot the rifle up to 169 times, which is too many to show to you here. So I will encapsulate.

Shot 51 went out at 541 f.p.s. Shot 61 went out at 558 f.p.s. Shot 71 went 555 f.p.s. Shot 81 went 552 f.p.s. Shot 91 went out at 553 f.p.s. Shot 101 went out at 557 f.p.s. and shot 106 went out at 553 f.p.s. I am calling that the end of the useful shots. So Ton Jones’ method of adjusting the top hat got me 106 useful shots on a fill. In the last test that was done in Part 2 where the top hat was loose we saw 87 useful shots. This new method of adjustment gave us 19 additional shots within the useful range. The low for Basics was 511 f.p.s  on shot number 57 and the high was 565 f.p.s. on shot number 80. That is a spread of 54 f.p.s. for this pellet. I think that spread is too high, but I’m not yet ready to make that comment until you see the remainder of the test.

Off the regulator

Shot 107 went out at 576 f.p.s. and I felt the rifle was off the regulator. BUT  — look what followed. Shot 110 was 565 f.p.s. Shot 120 was 565 f.p.s. Shot 130 was 566 f.p.s. Shot 140 was 607 f.p.s. Shot 150 was 595 f.p.s. shot 160 was 559 f.p.s and I stopped shooting at shot 169, which went out at 515 f.p.s. The rifle began loosing velocity steadily after shot 143, which was a Basic pellet moving at 621 f.p.s. 

What I’m saying is although I called shot 107 as the point where the rifle fell off the reg, there were still 62 more shots that were fired! I think I need to tweak the top hat setting just a little, now that I know how it’s done.

That being said, I think I can now turn my attention to the accuracy of the rifle. The reason I did not test accuracy today was the rifle slowed down radically while I was shooting a group, due to the top hat turning. That isn’t happening anymore. I do feel that there could be 70-80 good shots in this rifle at around 570 to 580 f.p.s. with Basics, if the top hat is adjusted better. I would like to see the rifle fall off the reg and not have so many powerful shots remaining.

The pressure remaining in the reservoir at the end of today’s test (169 shots) was 800 psi. At the end of the velocity test in Part 2 there was also 800 psi remaining, but I only got 101 shots in that test and the starting and ending velocities with Basic pellets were very similar. Those two tight-fitting 007 metric o-rings are what made such a dramatic difference.

One last thing

Remember that picture of the o-rings under the top hat that you all didn’t like? That picture was taken BEFORE the velocity test in Part 2. Look at my 007 o-rings AFTER 169 shots in this test.

Edge 007 rings
After 169 shots the 007 o-rings are still in perfect alignment. That’s because these rings have a smaller inner diameter and squeeze the valve stem. Remember — they do not determine velocity. They just control how much air is wasted with each shot.
This picture was taken before my “Oh, phooey” realization below.


Coaches of junior marksmanship teams who have shooters with Edge target rifles need to pay attention to this report! This stuff is brand new and hasn’t ever been seen before. Setting up the top hat this way will significantly increase the shot count that your competitors get from a fill.

I think I can adjust the top hat out a little farther and increase the average velocity a little while also improving the shot-to-shot consistency. I don’t think I need to disassemble the valve or regulator to do this — just tweak the top hat a little more. I’m not sure of it though, and this report has taken me a very long time to create, so I’m finished for now. Stick with me and we will sort this out.

Oh, phooey! I could not stand it not knowing, so refilled the rifle to 3,000 psi, then rotated the top hat one revolution more out from the valve body and shot a final string of Basics. The first shot was 596 f.p.s., but with this Edge every first shot after a pause of some time (I had waited about 30 minutes) is abnormally high. The next 10 shots averaged 575 f.p.s. The spread went from 571 to 579 — a mere 8 f.p.s.

I will have more to say about this in the next report but, by golly, first I’m going to shoot some targets! I probably need to do another velocity test at some point. Maybe I will finish the air that’s in this tank and record the numbers but hold off on the velocity report until we have some targets to look at. We shall see.

A little about o-rings

by Tom Gaylord
Writing as B.B. Pelletier

An assortment of o-rings.

This report covers:

  • History
  • Flexibility is key
  • O-ring failure
  • O-rings as a face seal
  • O-ring-assortments
  • Hardness
  • Some o-ring facts
  • The seats or channels they sit in help o-rings work!
  • O-rings used other ways
  • Summary

An o-ring is a donut-shaped elastomer (pliable) seal that performs sealing functions for hydraulics and gasses. Airguns use o-rings a lot, and for different purposes. They help us enjoy our hobby with a minimum of fuss. But what do we know about them?


The first patent for an o-ring was by the Swedish inventor, J.O. Lundberg. It was granted in 1896. Not much is known about him, but Danish machinist, Neils Christensen who came to the U.S. in 1891, patented the o-ring in this country in 1937. No doubt his work originated from his development of a superior air brake that Westinghouse, a leader in air brake technology since George Westinghouse invented the first fail-safe railroad air brake in 1869, gained control of. In World War II the U.S. government declared the o-ring a critical mechanical seal technology and gave it to numerous manufacturers, paying Christensen a stipend of $75,000 for his rights. Long after the war was over and he had passed away his family received another $100,000

Flexibility is key

For an o-ring to work it usually needs to be flexible. One of the most noteworthy failures of an o-ring that was not flexible was the space shuttle Challenger disaster in January, 1986. Caltech physicist and Nobel laureate, Richard Feynman demonstrated that the cold experienced during launch as the rocket rose had hardened the large o-ring that sealed the right solid rocket booster to the point that it crumbled in failure. Let’s see why flexibility is so important.

An o-ring sealed two adjoining parts (top and bottom)

o-ring under pressure
When under pressure (gas is coming from the left in this drawing), the o-ring deforms and presses against the tiny opening at the upper right, sealing it tight.

In both drawings I have made the clearances between the parts larger than it should be, to make it easier to see.

O-ring failure

O-rings don’t just fail in aerospace applications. We have seen them fail from rigidity in airguns, too. Read the report titled Crosman Mark I and II reseal to learn a lot more about them. In those two reports we saw how a hardened o-ring crumbles when it’s removed, and how a fresh one reseals the airgun instantly.

Another way an o-ring can fail is if it extrudes (gets squeezed through) the opening it is trying to seal. That happens when the ring material is too soft for the application or the tolerances between parts are too great or the o-ring channel is cut improperly.

O-rings as a face seal

We also see o-rings used as face seals in some airguns. One common use is as the breech seal of a breakbarrel airgun. I have shown you this many times as I rebuilt Diana air rifles over the years. The most recent was the Diana 27S, whose breech seal had hardened from the passage of time. When I replaced it with a fresh o-ring the rifle gained some velocity, though not the 300+ f.p.s. I initially thought.

Diana 27S breech seal
Diana breech seal.

Not all breakbarrel breech seals are o-rings, even though they may look like they are. Weihrauch has used specially designed breech seals that appear to be o-rings when they are installed, but when you examine one outside the airgun you see a big difference.

Weihrauch breech seals
Weihrauch breech seals look like o-rings when they are in the gun, but they are not.


Beware, because here comes The Great Enabler! Several months ago I realized I was buying o-rings one at a time for projects as I needed them. That’s not the wisest thing for a dedicated airgunner to do. So I went online and searched for assortments of o-rings. I found many and it came down to two things — what did I need and how much did I want to spend? For me this is a business expense, so yes it comes out of my pocket — sort of. But when I buy something like this I get to spend it before Uncle Sam can.

When you need an o-ring they are specified by their internal diameter (ID) and the diameter of the ring material. The outside diameter (OD) of the o-ring is just given for informational purposes, because when you think about it, the ID and ring material size determine the OD automatically.

I bought an SAE assortment and a metric assortment, but because they are pliable , they will interchange if they are close. If you want to get really picky, o-rings come in aerospace standard 568 (AS568) and ISO 3601 sizes. They also come in a wide variety of materials with Buna (Nitrile), Neoprene, Urethane, Viton, Teflon (PTFE) and Silicone being some of the most common. Airgunners tend to use Buna, Teflon and Urethane. Buna is more pliable and Urethane is more resistant to tearing and abrasion.


A lot of people use the term durometer when referring to o-rings without understanding it. A durometer is a test instrument that measures a nonmetallic material’s resistance to puncture and abrasion. The Shore scale is used. When we talk about o-rings I see the term 90 durometer tossed around a lot. A 90-durometer rating only has real meaning when matched to the Shore hardness scale to which it applies. On the Shore 00 scale a 90 rating is medium hard, while on the Shore D scale a 90 rating is extra hard — almost as hard as it gets! Your car’s tires are a zero to 10 on the Shore D scale and a 90 on the Shore 00 scale.

Some o-ring facts

1. To perform correctly, a hard o-ring needs tighter tolerances than a softer o-ring.
2. An o-ring usually needs lubrication to do its job – but not always.
3. When an o-ring seals something, it only needs to be finger-tight.
4. An o-ring can look fine yet hide a tear or a puncture that will leak under pressure.
5. An o-ring can look ratty yet still seal perfectly.
6. The durometer rating of an o-ring can change over time, as it hardens.

The seats or channels they sit in help o-rings work!

If the seats are too wide or too deep, the o-ring will not seal the joint as intended. Also, the shape of the o-ring seat or channel is somewhat important. While there is a lot of room for slop with an o-ring (that is one of their endearing qualities), you can’t get away with murder. A perfectly square channel with no radius in the corners may present sharp edges to the o-ring under pressure. It can cut the o-ring, causing it to fail quickly!

O-rings used other ways

Besides seals we find other uses for o-rings in airguns. Sometimes they are used to hold things together — sort of like precision rubber bands. I find that a lot in silencers. And a number of rotary magazines use o-rings to hold the pellets inside in place. I’m sure they are used in other ways, as well. We owe a lot to the common o-ring


There is a lot more to know than what I have presented today. These have just been some of the basics about o-rings. We deal with them so much I thought it would be nice if we knew a few things about them.

AirForce Edge 10-meter rifle: Part 5

by Tom Gaylord
Writing as B.B. Pelletier

AirForce Edge
AirForce Edge.

Part 1
Part 2
Part 3
Part 4

This report covers:

  • Behind the curtain
  • Field measurements
  • Test 
  • Low velocity
  • Different valve
  • H&N Finale Match Heavy
  • RWS Meisterkugeln Rifle
  • Shot count
  • Short on air?
  • Hammer spring
  • What else have I learned?
  • Summary

Today is unusual because I’m doing a back-to-back report on the AirForce Edge. I don’t normally do that, but I discovered some very interesting things that will probably help a lot of you with precharged pneumatic airguns of any kind. Also, I got into this project and just couldn’t stop until it was finished. I know you know what that’s like. Let’s get to it.

Behind the curtain

There were several things I did not tell you in Part 4 last Friday. I did them then, but the results were outside the scope of the report, so I held off. Today they will make a lot more sense.

Field measurements

First, let me show you how precise measurements can be done in the field without gauges. When I worked at AirForce Airguns I tested and adjusted all the valves for their rifles. Over the course of three years I worked on several thousand valves.

Things were simpler in those days as there were fewer models and therefore fewer types of valves to build. There were standard valves for the Talon and TalonSS and Hi-Flo valves for Condors. Each valve had its “top hat” — the adjustable piece that connects the valve stem to the hammer — and it had to be adjusted to a precise height. That height affects the length of time air can flow through the valve and we had a specification for the top hat clearance for each valve. Besides that the valve return springs were adjusted to a specific amount of force when the valves were built. The combination of those two things determined the power range of the rifles, but you have to remember that these rifles also have external power adjustment wheels, too, so a balance had to be maintained.

When I tested the valves I adjusted the top hat clearance for each one with a feeler gauge, which is a precise way to do it. But if I was under the gun to set up a gun for testing, or if a customer was sitting in the office, waiting to take delivery of his gun that had been repaired, I could also adjust the valves with coins. New coins are very uniform and it wasn’t long before I learned which one to use for which valve. Instead of walking into the repair shop and searching for the feeler gauge I could stick the right coin under the top hat and tighten it against the coin. That would get me to within a couple thousandths of the specified measurement, and that was within the acceptable tolerance.

So last Friday when I changed the valve on this Edge I noticed that the top hat of the new valve I was installing seemed too low. I didn’t have a feeler gauge to measure the gap, so I used an American dime. I used a new dime that had no wear. It fit the gap tight. A dime has a thickness of 1.35mm or 0.053-inches. According to AirForce the clearance should be 0.070-inches.

Edge top hat gap

This gap under the top hat determines how long the valve stays open.

Edge top hat dime

A new American dime fits into the top hat gap, determining the clearance quite well. This is too tight for an Edge valve.


Once the new valve was in the tank I tested it. I got the numbers you saw last Friday. At around 620 to 630 f.p.s. the gun was shooting about 100 f.p.s. too fast. As you saw, that additional velocity reduced the shot count from over 100 to 45 shots per fill. That was unacceptable, so I tried another field fix. I put an o-ring under the top hat. That both reduces the valve stem travel distance as well as adding a little rebound to the valve, to make it close faster. 

Edge top hat o-ring

An o-ring fits into the gap under the top hat.

Low velocity

When I tested the velocity with the o-ring in place here is what I got.


I stopped at this point. Seeing the numbers rise in the beginning, I was hoping they would rise to where I wanted them — in the low 500s. But as you can see that didn’t happen. So, using an o-ring with this valve wasn’t the solution.

I learned from talking to the AirForce representative that the original Edge valve does have three o-rings under the top hat. That was news to me, because in my day at the factory we didn’t put o-rings there. I did in my own guns, but that was a private thing the owners of AirForce guns did back in the early years of this century.

Different valve

I had a second spare Edge valve that had two o-rings in the gap and I wondered if that valve would work. Then I read the date code on each of the three air tanks — the one that came with my rifle and the two spares that Gene sent me. My rifle is serial number 10 and its tank has a production date of October, 2009. One of the two tanks with holes drilled in them (for trade shows, where you cannot have guns that can fire) was also dated October 2009. The other one with the valve that has the two o-rings is dated January 2012, which is a little over two years later, when the Edge was in full rate production. Not only does it have the o-rings that the other two valves don’t have, there are also different parts inside the valve. So changes were made to the design from the very early days to the days of high-rate production.

The day after doing Friday’s test I swapped valves again and installed the one with the o-rings in my rifle’s tank. When I fired the first shot I could tell that it wasn’t as loud as it had been the day before. Let me show you the first few shots. These are with the 7.7-grain RWS R10 pellets.

1………..DNR — first shot to test that the valve functions

As you can see, the velocity dropped off after the first couple shots. I think that represents the new valve settling in, because some of the parts came out of the valve when I swapped it and had to be put back inside. The Edge valve is made differently than the other AirForce smallbore valves and doesn’t stay entirely together when it comes out of the rifle. The parts in the rear of the valve are held in place by the regulator.

Following the first 8 shots that I thought had settled the valve down, I shot the first string with ten more of the 7.7-grain R10 pellets. Here is what I got.

Shot…..Tot. Shots…..Vel

The average for this string was 524 f.p.s. The range went from a low of 521 to a high of 528 f.p.s. — a spread of 7 f.p.s. At the average velocity this pellet produced 4.7 foot-pounds of energy. It was a little slower than I thought after the first 8 shots, but it’s still quite good.

This is right on for an Edge. When I tested a factory gun back in 2010 I got the same velocities from a 7.56-grain pellet.  I shot the string above immediately following the first 8 shots, and that will become important in a moment.

I’m keeping track of the total number of shots on the fill. That way we can get a shot count at the end of the testing.

H&N Finale Match Heavy

H&N Finale Match Heavy pellets were tested next, but there was a 10-minute paused between the end of the last string and the start of this one. I’m telling you that for a reason that will become clear in a moment. Let’s see what happened.

Shot…..Tot. Shots…..Vel
1………..19…………535 — huh?
12………30…………536 — nailed it!

This is a string of 12 shots, because of the higher velocity of the first one. Notice that after that shot the velocity drops back down into the low 520s and lower. I noticed that and wondered whether, by leaving the rifle sitting for 10 minutes, it allowed more air to pass through the regulator. Remember the story of the slow regulators in the FX Dreamlite rifle and the Artemis PP700S-A PCP pistol?

If I was right about my theory and waited for some time before shooting the final shot, it would be much faster again, like the first one. I waited 12 minutes and then recorded a 536 f.p.s. shot. So, I have learned something valuable about this Edge and the valve that’s in it. The first shot after a long (10 minutes or longer) rest will be faster than the shots that immediately follow. As you can see, that is exactly what happened — twice!

If I disregard the first and 12th shots in this string, I have 10 that average 519 f.p.s. The low is 510 and the high is 525 f.p.s., so a spread of 15 f.p.s. That’s a little large for a regulated PCP, but of no consequence for a 10-meter target rifle, because the distance to the target is so short. At the average velocity for this string, this pellet produces 4.89 foot-pounds at the muzzle.

I am getting very comfortable with this rifle the way I now have set it up. Time to test it with the last pellet.

RWS Meisterkugeln Rifle

The RWS Meisterkugeln Rifle pellet is the final pellet I will test today. It weighs 8.2 grains, so it’s the heaviest one I’m testing. I waited 2 hours after the last string so I’m expecting that higher velocity first shot again.

Shot…..Tot. Shots…..Vel
1………..31…………525 — yep!
12………42…………508 — Oh oh! Theory failed!

The 10-shot string that falls from shot 32 to shot 41 averages 499 f.p.s. It ranges from a low of 491 to a high of 514 f.p.s. — a spread of 23 f.p.s. That’s pretty large for a regulated gun, so the Meisterkugeln Rifle pellet may not be the best pellet for the Edge in its target configuration. Shooting at a target will tell us that.

At the average velocity Meisterkugeln pellets developed 4.53 foot-pounds of energy.

My theory about the first shot being faster was spot-on, but I waited 13 minutes between shots 11 and 12, and shot 12 only registered 508 f.p.s. I would have predicted something in the 520+ f.p.s. region. Is the rifle running out of air? Or is my theory sort of right but not always?

Shot count

If the rifle is now healthy we should see something around 100 shots per fill. So here we go, shooting the 7.7-grain RWS R10 pellet whose average before was 524 f.p.s.

64…………535 Sign of nearing the end of the string

There is a lot to learn from this string. First, you can see that the rifle fell off the reg after shot 67. Shot 68 went out at 514 f.p.s. and all subsequent shots were slower. But wait just a minute! Shot number 48 was also 514 f.p.s. Why do I say that wasn’t the place where the rifle fell off the reg? I say it because the shots that followed that one all went faster, so the reg was still operating.

Next, look at my comment after shot 64. When I saw that out-of-profile faster shot I knew the rifle was nearing the end because that’s what often happens when the air pressure drops. I see it all the time in unregulated guns — though this is the first time I can remember seeing it in a regulated gun. That tells me something is still not right with this Edge. And that fact gives me the next discussion point.

Short on air?

Why is this Edge giving just 67 shots on a fill when the one I tested in 2010 gave over 100 shots at very similar velocities? I think more is wrong with the rifle than just the valve. I think either the hammer spring has been replaced or the hammer — or both! I said that at the end of Part 4 and RidgeRunner assured me that the hammer and spring had not been modified. But what if they were changed before he got it from my late friend Mac? What if someone had modified them before? One way to tell is to pull the barrel and remove both parts for a look, so I did. And, what to my wondering eyes should appear…?

Hammer spring

The hammer spring is from a Talon rifle; it’s not an Edge mainspring at all. An Edge spring is just two inches long and coiled around a special piece of plastic. And the hammer that came out of the rifle is even worse!


The hammer in this rifle is a steel affair. It’s obviously homemade. AirForce would never turn out a part this crude! The Edge hammer is lightweight plastic. This thing weighs way too much!

Edge spring hammer

The mainspring is from a Talon or TalonSS. The hammer is just a piece of steel tubing that’s been cut to fit. It’s too crude to be an AirForce part, plus it’s way too heavy and wastes air.

When I replace these parts with the genuine items I bet we will see a change in performance. I know I will feel better, now that heavy hammer is no longer beating the valve apart.

I will say this, souping the rifle up to shoot faster had no negative effect on the reg. As long as the tank was not filled above 3,000 psi, the reg was operating in its ideal design environment. Some PCP owners think if they overfill their reservoirs they will get more shots per fill and that is true — until the regulator that wasn’t designed for that higher pressure gives up the ghost.

What else have I learned?

Discovering these bogus parts changes everything. I thought this rifle was too loud for an Edge, once the silencer was removed. It turns out the noise was caused by the powerplant wasting 40 percent of the available air. That is what the homemade heavy hammer and the too-strong mainspring get you.


There is more work to be done on this airgun, followed by a retest. I bet we see a marked difference when the rifle is completely stock.

After I have tested the Edge in its original configuration I plan to re-test the Crosman Challenger PCP and then do a comparison between the two rifles. This series is like an historical one with the exception that both of the subject rifles are still being made and sold.