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! read more

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. read more

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. read more

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 read more

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. read more

Some talk about airgun lubrication: Part 1

by Tom Gaylord
Writing as B.B. Pelletier

This report covers:

  • Why do we lubricate?
  • The Meteor’s needs for lubrication
  • Leather piston seals
  • Velocity
  • Watch the performance
  • Synthetic piston seals
  • Summary
  • Other lubrication requirements

Yesterday a reader asked why I bothered with Tune in a Tube. Why didn’t I just clean the Meteor Mark I when I had it apart, lubricate with moly grease and be done with it? That tells me there are a number of readers who don’t really understand what is involved with airgun lubrication. So today I thought I would discuss it a little.

Why do we lubricate?

This is a good place to start. In fact, from the reader’s comments, it seems to be at the core of misunderstanding. Don’t we just lubricate to reduce friction?

Friction is a principal reason for lubrication. But there is more to it than that. Sometimes we want to reduce friction by a certain amount, while retaining some part of it that’s needed for proper operation. Otherwise, moly (molybdenum disulphide) would be the answer to everything. Some airgunners think it is. The reader who wrote the comment that got me started on today’s topic said that very thing — that I should just clean the Meteor’s parts and lube everything with moly and be done with it.

That would be a disaster! Let’s look at that airgun and see why.

The Meteor’s needs for lubrication

The Meteor was buzzing when it fired. Buzzing is caused by excessive tolerances that allow the powerplant parts to vibrate when the gun fires. Moly will have no affect on that. The parts may move faster than they did before when lubed by moly, but they will still bang together and vibrate in an annoying way.

What is needed is one of two things. Either the parts must be tightened in some way so there is less sloppiness or they must be surrounded by a material that causes the vibration to stop quickly. Tune in a Tube does the latter. While it does provide lubrication, the ability to stop vibration is its principal feature. Add to that the fact that it can be applied to a gun without disassembly and you have a wonderful product for a spring piston airgun. And a mediocre one for a CO2 or pneumatic gun, whose needs for lubrication are different.

I will address those other powerplants later in this series. Let’s stay with the Meteor for now. The Meteor is made as cheaply as it can be. Its piston is sheet metal that’s formed into a cylinder and welded, top and bottom. That kind of construction does not lend itself to the attachment of synthetic bearings called buttons, which are the number one way to eliminate slop for a piston . You saw me use buttons on the piston of the Diana 45 I tuned in the special 10-part series I did last year. Part 6 of that series shows most of the tricks I would normally use to tune a spring gun, but the Meteor’s thin metal construction doesn’t allow most of them. Because of that, Tune in a Tube is an ideal product for the Meteor. The intended use is a large part of selecting the correct lube.

For the Meteor piston, piston seal and mainspring I need a lube that will dampen vibration, reduce friction and also seal the compression chamber. Tune in a Tube with do the first two, and oil will seal the compression chamber. But — what kind of oil? The Meteor has a leather piston seal, so let’s discuss that first.

Leather piston seals

Leather piston seals need to be flexible to seal the compression chamber. That takes oil. Is the oil a lubricant? Yes, but in this case it’s being used for three good reasons. First, because it keeps the leather seal pliable, allowing the leather to flex and to therefore seal the air in front of it. Second, being oil, it lubricates the seal, reducing friction so the seal and the piston it’s mounted on will move as fast as possible. And third, being oil, it evaporates slowly, which means the seal will stay pliable longer. But longer than what? Well, longer than water, for example.

Water will lubricate the leather and make it pliable. A water-soaked piston seal will seal the compression chamber about as well as one soaked in oil. But water evaporates rapidly and will dry out. When it does, the leather will shrink and harden. If left that way, it will break up in small particles every time it is moved, as in firing. And, if left for long enough it will eventually dry completely, allowing the leather to deteriorate by a process we call dry rot. Oil may dry to a point, but even when appearing dry some will remain for years, preserving the leather if it isn’t worked too hard. I have seen the leather seals in airguns that were over one-hundred years old, and they were still in working condition because they had been oiled.


The velocity of the airgun also plays a factor in the choices for lubricants. The Cardews showed in their experiments that were documented in the book, <i>The Airgun from Trigger to Target</i>,       that when a spring piston airgun approaches 600 f.p.s. muzzle velocity it starts burning some of the lubricant in the compression chamber. That is called dieseling. Like any other internal combustion engine, this burning of oils generates energy of its own. In an experiment the Cardews shot a 14.4-grain .22-caliber pellet in an HW 35 at 636 f.p.s. when the gun was properly lubricated. When the same gun was fired in a pure nitrogen atmosphere where combustion was not supported, the same pellet only shot 426 f.p.s. This proved that combustion was generating part of the energy in that airgun.

My BSA Meteor Mark I shoots light lead pellets at greater than 600 f.p.s. So it is safe to assume that it, too, is dieseling with every shot. If water was used on the leather seal, the gun couldn’t diesel and the resulting velocity would be much slower. But consider this. If I used a type of oil that combusts readily, such as one made from petroleum, the gun might go from dieseling to detonating, which means exploding with every shot.

Therefore, for guns that shoot in the high 400s to the mid-500s, like Diana 25s and 27s, I recommend a piston seal oil that’s petroleum-based, like Crosman Pellgunoil. For guns that approach 600 f.p.s. and more I recommend high-flashpoint silicone chamber oil. Now you know the answer to what oil to use in a spring gun that you suspect has a leather piston seal. It’s based on the gun’s potential velocity, and if you don’t know what that is, watch the performance of the gun after you oil the piston.

My final comment about water on leather seals — don’t do it! That was mentioned for the purpose of discussion, only. Water inside a spring gun would rapidly oxidize and cause the gun to rust.

Watch the performance

If the gun you have oiled smokes after each shot without any noise, you are using the right type of oil on the piston. It may detonate a few times at first, but two or three explosions is all you should hear. If it keeps on exploding, you used the wrong type of oil. Since the seal is leather, just wait a few months, then oil it with silicone chamber oil from then on.

Synthetic piston seals

The oil for synthetic piston seals does something different than the oil for a leather seal. A modern synthetic seal is self-lubricating, which really means that the seal material has a very low coefficient of friction. It doesn’t need oil to work its best — at least not from the standpoint of friction.

A synthetic seal uses oil as an additional air barrier between the edge of the seal and the compression chamber. Like the oil in your car’s engine, the oil in your airgun compression chamber just makes the piston seal better. Don’t use too much oil, though, because the act of firing will vaporize some of the oil and cause it to detonate inside the compression chamber.

Synthetic seals come in all modern airguns, but since most of them shoot faster than 600 f.p.s., I advise everyone to use silicone chamber oil for their seals. It saves me having to explain all that is in this report, every time I talk to a new airgunner.


Today we have discussed lubricants used for two purposes. The first is to reduce vibration between moving parts in a spring-piston powerplant. And the second is to lubricate the piston seal.

When it comes to the piston seal we discussed the three purposes for oiling leather piston seals, and what types of oils work best. We learned that it depends on the power the gun produces. We also discussed what lubrication does for synthetic seals, and how that differs from the needs of leather piston seals.

I held nothing back today. If this report put you to sleep, my advice is to have someone else tune your spring guns. And, I’m just getting started. There are other lubrication requirements that deserve a thorough presentation as well.

Other lubrication requirements

Sealing pneumatic and gas reservoirs and valves
Reducing friction on metal parts
…heavy wearing parts like linkages
…piston bodies and spring guides
Oiling pellets

As you can see, there is a lot to lubricating airguns, and I plan to tell it all.

Mainspring compressor

by Tom Gaylord
Writing as B.B. Pelletier

mainspring compressor
Mainspring compressor.

This report covers:

  • Can you make a mainspring compressor?
  • BSA Meteor
  • Description
  • Bridge
  • Headstock
  • Tailstock
  • Legs
  • General

Today I’m going to show you a mainspring compressor that I will use in tomorrow’s blog. I was asked this week by a new reader to show the tools needed to safely disassemble a spring-piston airgun. Here is the request.

Great web sight!  As a “newbee” to air rifles, I find it a wealth of info!  Having a hard time trying to start a new post in the blog forum..  Specifically, I’m looking to find out if anyone makes proper tools for the correct disassembly of the Benjamin Trail NP XL 1500.. Looking for a proper end cap removal tool, and a spring compressor.  I was an armorer for years in LE, with an incredible amount of proper tools for “firearms”.  Just want to make sure that maybe there’s a place to purchase proper tools for air rifles out there.


I didn’t answer him that gas springs, which the Crosman/Benjamin Nitrop Piston is, usually do not require mainspring compressors, because I knew this blog was forthcoming. I wanted to work it in, so I told him I would answer him in a blog later in the week.

The truth is, gas springs — and, yes, that is the correct generic name for all of them, be they Nitro Pistons, gas rams, gas struts or anything else — are usually under no preload when they are in the rifle. If there is any preload (spring under pressure when it is in the gun) the travel is no more than 1/2 inch or so. So usually you can just drift out the pin or remove the bolt that holds the end cap in the spring tube and the gas spring drops out as a unit. Don’t disassemble a gun unless you know for certain how it comes apart, but this is what you will usually find.

We are here today to learn about a mainspring compressor that can be used to disassemble almost any spring-piston airgun that has a conventional coiled steel mainspring. I have been using a compressor like this one for over a decade and in fact I helped with its development. This compressor was invented by B-Square, under the direction of the company owner, Dan Bechtel. I consulted with him during its development and the result was a tool that hundreds of airgunners now own. But to be honest, mainspring compressors are not very exciting, so airgunners tend not to buy them. They tell themselves that can make one if need be, and then I hear all the whining and crying when the day finally dawns that they really do need one.

Can you make a mainspring compressor?

Yes, you can make a mainspring compressor. In fact building a mainspring compressor is so easy that hundreds of them have been made by shooters over the years. Some guys have even made them for resale, but every one of those guys stopped when they discovered how poorly mainspring compressors sell. A mainspring compressor is like a good pair of pliers. When you need a pair almost nothing else will suffice, but when you don’t need them you never even think of them. No, I will go even farther. To a person about to disassemble a spring gun a mainspring compressor is like a bench vise. It is absolutely essential.

Don’t get me wrong — airguns can be disassembled without using a compressor. Some guns, like the Air Arms TX200 Mark III, are so easy to disassemble that a compressor is never used. But they are the exception. Most spring guns do require a compressor if you want to be safe and have no more than two hands.

BSA Meteor

Tomorrow I’m going to use this new compressor to disassemble my new BSA Meteor Mark I for you. This is so you can see what the innards look like before I start the Tune in a Tube test. That test will be followed by a real tune, so we can compare the results after each tune. If you want to know more about how a BSA Meteor comes apart, read the 9-part report.


This new compressor is sold by Sun Optics. It is fully adjustable and is designed to disassemble the barreled actions of spring rifles and pistols that have been removed from the stock. The parts that contain the action (called the tailstock and the bridge) adjust up and down stainless steel tubes which is what all the holes are for. Sun Optics has even made some improvements over the compressor B-Square made. The B-Square compressor used steel conduit for the legs instead of tubing. The holes in the legs of the Sun Optics compressor are all chamfered for smoother adjustability. I noticed the difference right away.

chamfered holes
The new stainless steel tubes (top) have chamferred adjustment holes. I had to grind the burrs around the holes on the old compressor myself (bottom).


The bridge is the part of the compressor that keepss the spring tube from flexing to one side when the mainspring is no longer trapped. This flexing is the second biggest problem you’ll have when you disassemble spring guns. Controlling the end cap is the only task that’s more important.

The bridge has screws that adjust to center the spring tube in line with both the headstock and the tailstock. That gives you the most working room around the barreled action.

On the old compressor the bolts on the bridge were all left raw. I protect the finish of my guns by wrapping the gun’s spring tube with a heavy leather belt that the screws cannot scratch through. The new compressor has plastic tips on each of these screws.

The tips of all the bridge adjustment bolts have plastic caps. No more leather belt to keep from scratching the spring tube!


One feature of the original compressor that made it the best on the market is the rotating headstock. It allows you to rotate the barreled action from side to side while still maintaining pressure on the end cap and therefore on the mainspring. This allows the positioning of the tube so pins can be aligned and/or drifted out. This is the key to the compressor, because many spring gun actions are held together by pins. The new compressor headstock rotates in the same way as the old one.

The new compressor headstock also has a hole in the center for a pin to a part the old compressor didn’t have. It’s a pusher block that’s used to disassemble certain spring gun actions, notably BSAs. Unfortunately this block is slightly too wide to fit inside my Meteor spring tube, so I will have to use the plastic pusher block I made when I disassembled my other Meteor. But if I owned this compressor I could easily shave the new block down to fit.

I will also have to enlarge the hole in the headstock, because the pin in the pusher block is too large to fit. It does fit the hole in the tailstock, but I don’t know anyone who would use it that way.

The headstock turns to allow access to different parts of the gun’s spring tube. This new headstock has a hole (arrow) for the pin of a new pusher block.

headstock with block
New aluminum pusher block comes with the new compressor. The pin at its base is too large to fit the hole in the headstock, so some drilling will be needed.


The tailstock is where the muzzle of the action rests. It adjusts along the two steel rods to fit the gun you are working on and give the headstock screw lots of room to travel. It also has a hole for the pusher block, though I cannot think of a reason to use it that way.

The new tailstock also lacks the raised bump the old tailstock had. That was inserted into the muzzle of the barrel, to keep it from walking when the action was under pressure.

The tailstock adjusts for the length of the gun. Hole is for the pusher block pin, but I don’t know how it would be used on the tailstock. Gone is the raised bump the old compressor had to keep the barrel from walking. read more