Posts Tagged ‘lubrication’

Airgun lubrication — pneumatics

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

Airgun lubrication — spring guns: Part 1
Airgun lubrication — spring guns: Part 2
Airgun lubrication — gas guns

This report addresses:

• What is a pneumatic?
• No. 1 lubrication need.
• A short pneumatic history.
• Which oil to use?
• Other lubrication.
• Wipe down.

This report was written for blog reader Joe, who asked for it specifically; but I know that many of our newer readers also found the information useful. Today, we’ll look at pneumatic guns. There are 3 very different types of pneumatic airguns — precharged, single-stroke and multi-pump — but I think they’re similar enough to cover all of them in the same report.

What is a pneumatic?
Pneumatic airguns store compressed air for one or more shots. Single-strokes get just one shot per fill and so do most multi-pumps, though there are some that do get multiple shots. Precharged pneumatics (we shorten the name to PCP) get many shots per fill.

Big bores, which are always PCPs, get the fewest number of shots per fill, but the smallbores (.177, .20, .22 and .25) get many. How many depends on the output power of the gun and the amount of compressed air that’s available (i.e., the capacity of the air reservoir).

No. 1 lubrication need
The most important reason to lubricate a pneumatic of any kind is to seal the gun. This is similar to gas (CO2) guns; but since pneumatics use air — which is thinner than CO2, their lubrication is extremely important. The seals in the guns are all sized to their jobs. In the case of o-rings, they sit in channels that assist in their sealing role; but without the right lubrication, all would be lost.

A short pneumatic history
Pneumatics are the oldest type of airgun, and their technology has evolved over more than five centuries. The first pneumatic guns used leather seals in all places to seal the reservoir as well as sealing the firing valve.

As time advanced, airgun makers learned how to lap (polish until smooth) valve faces of animal horn that is much better and less porous than leather. These valve faces would be hand-lapped to match the exact surface of the metal (brass or bronze) valve seats to which they were fitted. When the lapping job was finished, these valves would hold air much longer than leather. Leather was still used to seal the junction around the threads of the reservoir, so the guns still leaked down — but the amount of leakage was reduced by a significant amount.

[Note: Airgun designer John Bowkett determined decades ago that precisely machined stainless steel valve faces and valve seats work best of all, providing there's enough lubrication and the machining is correct. The contact surface of this type of valve is extremely fine and narrow; but if it's perfect, this valve will be very controllable. The downside is that valves made this way are still extremely labor intensive.]

Leather seals and horn/brass valves were still being used in big bore PCP airguns up through the 1920s. Smallbore PCPs didn’t come into being until 1980, when Daystate converted one of their tranquilizer dart guns into a .22-caliber sporting rifle they called the Huntsman. Daystate was the first company to build a modern PCP; and when they did, synthetic materials were both available and far better suited for pneumatic valves. At the same time, o-rings in properly cut channels provided the remainder of the sealing solution in place of leather — and the modern PCP was born.

Synthetic seals are less porous than animal horn and last far longer. They’re not as hard as stainless steel, so the mating surfaces of the valve do not have to be machined as precisely (they have a little give to accommodate slight imperfections in the valve seats). Synthetics make the modern PCP possible. And lubrication is what keeps PCPs sealed almost forever.

Leather seals in other pneumatics
Leather has been used for the peripheral seals in multi-pump pneumatics up to as recently as the 1950s. Just like the leather seals of old, the problem has always been how to keep the leather seals lubricated so they remain soft, pliable and doing their job. Oil was used originally in these airguns in the late 1890s. But times change and today we have better lubricants. Petroleum jelly will stay on the job many times longer than straight oil, so even the leather seals in your vintage multi-pumps can be lubricated for a long time.

Which oil to use?
That brings us to the big question of the day: Which oil to use? In this instance, there isn’t just one answer. For PCPs, the right oil needs to have a very high flashpoint so it isn’t prone to explode when subjected to high pressure.

I know of two instances in which petroleum-based oil or grease has caused an explosion in a PCP. One was a vintage PCP reservoir that was pressurized to around 800 psi. The interior walls of the reservoir were coated with grease to trap any dirt particles that might get in during filling. This is a common practice with such airguns; but this time the person who greased the reservoir used petroleum grease instead of organic-based (animal) grease. The reservoir blew apart at the soldered seam! Fortunately, no one was hurt.

The other instance was one I got from a news story, and the person involved was, unfortunately, killed when his modern PCP reservoir exploded. The article said he had apparently introduced regular household oil into the reservoir.

On the other hand, I’ve safely oiled PCP tanks hundreds of times with a couple drops of Silicone Chamber Oil through the air intake port. I put several drops into the fill port before the gun is filled. When the air blows in, the oil is atomized and gets on all the sealing surfaces inside the reservoir and valves.

The oil to use in a PCP is silicone chamber oil. For single-strokes and multi-pumps, the answer is different. For either of these types of pneumatics I use Crosman Pellgunoil. Neither of these types of pneumatics are pressurized nearly as high as a PCP, and Pellgunoil always does the trick.

Can other oils be used instead of Pellgunoil? Certainly. I’ve used Gamo Air Gun Oil in my single-strokes and multi-pumps for many years. I use it exactly as I do Pellgunoil for single-strokes and multi-pumps, but I do not use it in any PCP guns.

The thing about multi-pumps and single strokes is to keep their pump cups sealed and working well. These are the flexible pump heads that force air into the guns, either one time or several. They tend to get hard over time and lose their ability to seal, but keeping them oiled and in use frequently will prolong their service lives. Not using a pneumatic airgun is what really hurts it.

Other lubrication
For normal lubrication of moving parts, both Pellgunoil and Gamo Air Gun oil work fine. So do most gun oils, like Remoil. What you do not want to use is silicone chamber oil for this purpose because it doesn’t have enough surface tension to lubricate properly. Your parts will rub against each other and wear.

Wipe down
As always you can use the lubricating oils to wipe down your gun’s metal and wooden parts, but Ballistol neutralizes acidic fingerprints and lasts on the surface of metal far longer than plain oil. So, it gets my recommendation for this job. It also gets the nod for the insides of all airgun barrels.

Airgun lubrication is important, for the reasons mentioned in this 5-part report. Sealing is the biggest role lubrication performs, in all cases. We’ve looked at some very specific examples of products that should be used for the reasons stated. If you decide to substitute, you do so at your own risk.

Airgun lubrication — gas guns

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

Airgun lubrication — spring guns: Part 1
Airgun lubrication — spring guns: Part 2

This report addresses:

• Molecules versus atoms
• Crosman Pellgunoil
• Can’t over-oil with Pellgunoil
• “Fixing” leaking guns with Pellgunoil
• Transmission stop leak oil
• Oiling moving parts
• Ballistol

Let’s look at lubricating gas guns — and by “gas,” I mean CO2. What I’m about to say will also work on airsoft guns that operate on green and red gas, because both those gasses work similar to CO2; but there are no pellet or steel BB guns that run on any gas except CO2 (excluding air).

CO2 is a molecule — not an atom!
Many folks thought that high school science class was a waste, but in the curriculum there were things that matter to airgunners. How levers work is one of the most important things, and yet I still see youngsters grabbing breakbarrel rifles five inches back from the muzzle — as though the length of a lever has no significance! The fact that CO2 is a compound made of molecules is also important.

Atoms are very small. When they’re inside a pressure vessel (air is made of several elements that are atoms), they try to escape through the smallest holes imaginable — sometimes through pinholes in the casting of the metal. Molecules are combinations of atoms that are much larger than atoms, by definition. They also try to escape, but they need larger holes to get through. This fact is what saves the CO2 airgunner, and it’s also why CO2 guns can be made with larger tolerances. That makes them cheaper to build.

Crosman Pellgunoil is our friend
When I started seriously shooting airguns in the early 1990s, nobody talked about Crosman Pellgunoil. I didn’t even know if it did anything. Then, I met Rick Willnecker, the man who runs Precision Pellet — one of the top repair stations for vintage CO2 and pneumatic airguns. Rick always had a jumbo bottle of Pellgunoil on his workbench, and he applied it liberally to valves, seals and o-rings whenever he assembled a CO2 gun. He told me that I should always put a drop of Pellgunoil on the tip of every new CO2 cartridge before it was pierced.

You cannot over-oil with Pellgunoil
I asked Rick how much oil was too much. He said it is impossible to over-oil a CO2 gun with Pellgunoil. Apply it liberally. What doesn’t stay inside the gun gets blown out the muzzle. This was all news to me. I’d grown up with the bottlecap CO2 cartridges of the 1950s that leaked before you even put them in your airgun, and I thought CO2 was a gas that was totally unreliable. Rick’s revelation turned this around. I discovered CO2 is a very reliable gas if you use Pellgunoil.

bottlecap CO2 cartridge
In the 1950s and ’60s, Crosman was capping their CO2 Powerlets with bottlecaps that leaked a lot.

But the discoveries didn’t stop there. Soon after learning about the benefits of Pellgunoil, I bought a Crosman model 111 target pistol at a flea market for $35. It was in the original box and came with the original 10-oz. CO2 tank that Crosman sold with the gun back in the early 1950s. I bought this gun thinking it would have to be resealed. It’s seller told me it had laid in a closet for a minimum of 20 years before she brought it to this flea market, so how in the world could it possibly have any gas left in it?

Crosman 116 pistol and bulk tank
This .22-caliber Crosman 116 bulk-fill CO2 pistol and tank were sold up until the model 150 came out in 1956.

Well, that gun was still charged! What is even more important was the 10-oz. CO2 tank that came with it was also mostly full, so I was able to connect it to the pistol and charge it many times — for another 50 shots each time. Each time I charged the pistol, I applied more Pellgunoil, and that old pistol kept right on functioning for almost 2 years. When the seals finally did need to be renewed, I took the gun to Rick Willnecker, and he got me started in bulk-filling CO2 guns. I bought my first 20-lb. CO2 tank and the adapter to connect it to the 10-oz. Crosman tank, and I was off to the races. Since that time, I have owned five 20-lb. CO2 tanks and have been filling my own bulk tanks at home for more than 15 years. Where a CO2 cartridge costs about 50 cents, I pay about 5 cents for the same amount of gas!

But it didn’t end there, either. I discovered on my own that by using copious amounts of Pellgunoil, I could get non-functioning CO2 guns to work again. That’s when I started buying up old Crosman gas guns that were leakers and “rejuvenating” them with Pellgunoil. I still own a Crosman 180 rifle that I bought for $20. It has been holding gas for about 20 years so far!

Transmission stop leak oil
Dennis Quackenbush taught me this trick. He said he “fixed” a leaking Crosman 112 bulk-fill pistol with transmission stop leak oil — the stuff you get at the auto parts store. I had a Crosman 116 bulk-fill pistol that was a fast leaker, so I thought I would give it a try. I put several drops of this oil in the fill port connection of the pistol and filled it with CO2. That was about 2-1/2 years ago and that gun is still holding gas today!

transmission stop leak
Transmission stop leak oil (this is just one brand…there are several others) will swell and make supple the seals inside an older CO2 gun.

Several people wrote comments telling me that this oil would turn the seals in my airgun to mush and it would be an even bigger leaker than before; but as I said, 30 months have passed and that gun is still holding gas. So is Dennis’ gun. This stuff seems to work.

Oiling the moving parts of the gun
You can oil the moving parts of a gas gun with any good brand of gun oil, and I even use household oil (yes, 3-in-One brand) on mine. If you want to buy a good oil from Pyramyd Air, I have used Gamo Air Gun Oil for many years for this purpose. All you’re doing is providing simple lubrication, and oil is correct for that.

Finally, you can wipe down the gun — wood, metal and plastic — with Ballistol. Ballistol removes rust, protects against fingerprint acids, lubricates and generally is the single best lubricant for an airgun or firearm.

Airgun lubrication — spring guns: Part 2

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

Airgun lubrication — spring guns: Part 1

This report addresses:

• Identifing and lubricating high-stress parts
• Lubricating with moly
• Lubricating triggers
• Lubrication intervals
• Lubricating mainsprings
• General lubrication
• Preserving the airgun with oil

Well, the immediate response we got to the first installment of this report made it one of the all-time favorites. In that report, we looked just at the piston seal, which I said was half of the lubrication solution for a spring gun. Today, we’ll look at everything else.

Parts under high stress
The moving parts of a spring gun are the powerplant parts, the trigger group and either the barrel, when it’s used as to cock the gun, or the cocking mechanism if the gun isn’t a breakbarrel. When airguns were simpler and less stressed, all of these parts could be lubricated with gun oil or lithium grease. But today’s guns are stressed to higher limits and generally need something more specific and better-suited to each application.

The high-stress parts are the piston, spring guides, mainspring, cocking shoe or other linkage contact with the piston, barrel pivot bolt and the sear. Any part that has several pounds of force exerted on it should be considered a high-stress part. In a vintage gun, I still use lithium grease on most of these parts. But for the sear, where I want the minimum resistance, and for the pivot bolt, which takes the force of cocking, I’ll use a grease that’s impregnated with molybdenum disulfide. Moly is not a grease, by itself. It’s a metal that, in the form molybdenum disulfide, is a solid lubricant that bonds with metal surfaces and provides a low coefficient of friction between the treated surfaces. It’s highly resistant to wear and remains in place for a very long time.

I use products like Air Venturi Moly Metal-to-Metal Paste for this application. I also have a half-pound of molybdenum disulfide powder that can be brushed onto ferrous parts and then burnished in.

Dr. Beeman warned against using moly on triggers, as it would make them too slippery to work safely. I was an early proponent of applying moly to sears. But — and this is extremely important — the trigger has to be adjusted perfectly, or it will become unsafe. No trigger should ever rely on friction to make it safe. It should rely on geometry for its safe operation; and if it cannot depend on that, then lubricating it with moly is very unsafe. I’ve had several improperly adjusted airgun trigger sears slip and allow the guns to fire without warning, so Dr. Beeman’s caution is well-taken.

The benefits of using moly in the right places are reductions in the cocking effort and in the trigger-pull. But it takes experience to know when to apply moly and when not to. The only way to get this experience is to lubricate many airguns and watch them as they perform.

A good oil for all other applications is RWS Spring Cylinder Oil. It can be used for general lubrication of hinge points and even the mainspring, itself. Use something like this when I recommend using oil.

Lubrication intervals
Once lubricated with moly, the job will last for years and even decades before needing lubrication again. Greases like those with lithium in them are more prone to dry out and harden. They must be monitored. You can do this by eye if the greased part is visible — such as the mainspring, by looking through the cocking slot. Or, you can do it by watching the gun’s performance. This is done both by feel and with a chronograph. Here is yet another reason to own a chronograph — to evaluate the health of your spring guns.

Notice that I haven’t told you exactly how often to lubricate your guns. That’s because it varies depending on use, climate, storage and the products you use. There’s no way to accurately give a lubrication schedule with all these variables. All you can do is watch your spring guns and know when to act.

Mainspring lubrication
“They” (the people who make and sell airguns) sell oil for lubricating mainsprings. Surely “they” know best. Right? Sometimes they do, and other times they’re just copying what has gone before. If you get a new airgun (whether it is brand new or just new to you) and you note that the mainspring is bone dry, then of course a little oil on the spring would be a good thing. Nothing inside your spring gun rubs against other metal parts as much as the mainspring. So, some oil is better than no oil. But oil isn’t the best lubricant for mainsprings.

A coating of moly paste is much better. Make sure you get it around the entire circumferance of the spring wire, because the spring rubs the guides on the inside of its coils…just as the outside of its coils rubs the inside of the piston.

Mainsprings are one part where some experience comes in handy. If the gun is lower powered, like a Diana 27 or a Slavia 631, I like lithium grease the best. When it migrates forward into the compression chamber, it doesn’t detonate in these guns. Instead, it lubricates the piston seal; and because it does, I use it heavily on these mainsprings.

In more powerful guns, starting at the FWB 124/Diana 34 level, I switch to moly for mainsprings. When the grease that suspends the moly moves forward, it can cause problems, but since I lubricate very lightly with this grease, there’s seldom a problem. That is what I mean by experience making the difference.

What about gas springs?
Gas rams or gas struts, to use their colloquial terms, don’t need the same kind of lubrication as steel springs. The gas piston unit itself is lubricated internally, so you never have to do anything with it. And many of them have synthetic bearings on the outside that suspend the moving parts, isolating them from the rest on the inside of the airgun.

Nitro Piston 2 buttons
The rear of the Nitro Piston 2 piston is buttoned for friction and vibration reduction.

Moly should be used for the bearing areas of a gas spring and use it very sparingly. These units are very quick and will detonate petroleum lubricants if they’re present.

The rest of the gun
Once again, experience is needed, but it boils down to using moly on high-stress parts like the baseblock spacers on a breakbarrel and oil on the common linkage parts.

base block spacer
Here’s a telling photo. The baseblock spacers (the one that looks like a washer) on either side of the block should get some moly on both sides, as well as the pivot bolt (bottom left). The other parts, like the cocking link, only need oil.

Lubing the barrel?
The barrel doesn’t need to be lubricated. Spring guns are always expelling tiny droplets of oil and grease into the bore. This is enough lubrication for the bore if lead pellets are used. I can’t tell you what to use when lead-free pellets are fired because each material has its own requirements. I would contact the manufacturers for that. Not the dealers — the makers of the pellets.

One last thing
Finally, you’ll want to wipe down the entire gun…metal, plastic and wood…with Ballistol to protect against corrosion and damage from acidic fingerprints. This is the way to store your guns for a long time without worrying about rust. Check them from time to time and renew the external oil coat as needed.

I hope this 2-part report addresses your concerns about lubricating spring-piston airguns. We still have to look at pneumatics and gas guns separately.

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?

What is a tune?

by B.B. Pelletier

Announcement: Bill Cardill is this week’s winner of Pyramyd Air’s Big Shot of the Week on their airgun facebook page. He’ll receive a $50 Pyramyd Air gift card. Congratulations!

Bill Cardill submitted this week’s winning photo for BSOTW.

Tune is slang for tuneup, and in airguns a tuneup can range from a quick lubrication all the way to a major overhaul of the powerplant and trigger. Everything in between these two extremes is also fair game. So, lesson one is that a tune can be anything that changes and hopefully improves the airgun’s performance.

I’m going to address a breakbarrel spring gun in today’s report. Other powerplants can also be tuned; but the steps are different, and the results will differ from what you get with a spring gun tune. Since the majority of airgun tunes are performed on springers, it’s appropriate to look at them first. And the breakbarrel is the No. 1 type of spring gun.

Victor asked what was meant by a tune, but I suspect that others would like to know what’s involved, as well, so today we’ll look at airgun tuning in all its complexity. Let’s begin with a brand-new spring gun and see why we would tune it and what might be done.

Smoothing the edges
Most new spring guns have sharp edges on all the mating powerplant parts. Sometimes, these edges interfere with the movement of the parts. These edges are worn down during a long break-in period, which is why a gun gains velocity as it wears in. But you can also remove these edges and burrs with small files, and that is one thing that a tuneup can do.

Key places to look are the cocking slot, the piston slot, the cocking linkage and, if there’s an interface between the linkage and the piston, that’s a prime place to look for burrs and sharp edges. The forward edge of the cocking slot is especially important, because it can slice a new piston seal when it’s installed…and that will ruin the seal. The end cap and sides of the trigger mechanism should also be checked.

The action forks that the pivot bolt passes through is another place to look for burrs and sharp edges, as well as the sides of the baseblock that the barrel is pressed into.

There are also burrs and sharp edges that don’t affect the operation of the powerplant. These do not go away with use and they can be left alone if you like. However, if you plan to take the powerplant apart in the future, these edges and burrs will be waiting to cut you.

Probably the most common thing done during a tune is lubrication. New guns can have either too much grease or not enough. And most of them have the wrong kind of grease. The factories use a general machine grease, but there are much better greases that can be used.

For metal-to-metal contact, nothing is better than grease that contains a high concentration of molybdenum disulfide. Moly isn’t a grease — it’s a solid particle that’s ground very fine and mixed with grease for application. When it comes in contact with metal under some pressure, the particles bond with the metal on the surface, forming a layer of extreme low friction. That layer is durable and allows other metal to slide across the surface it’s on.

We don’t appreciate how low-friction moly is, because the grease it’s in raises the coefficient of friction. But custom tuners are known to burnish certain parts of a gun — like the inside of the compression tube — with dry moly particles. This process takes a long time, as the moly doesn’t want to cooperate; but once it’s, done you have a surface with very low friction. Jim Maccari and I split a pound of moly powder, and my half was in several large bottles. It’s a lifetime supply for a full-time tuner!

Another place where moly powder comes into play is on the mating trigger sear surfaces. I’ll have more to say about this in a moment, but this is a custom tuner’s trick. The action fork and baseblock can also benefit from a burnish of moly.

I don’t burnish anymore, though. Moly grease, such as Air Venturi Moly Paste, will do the same thing over time as it gets worked into the action through the process of shooting.

But not every springer needs moly grease. The older guns with leather piston seals actually do better with a white lithium grease. The grease serves as fuel for the constant dieseling of all spring-piston guns, and leather seals burn more fuel than synthetic seals do. For this same reason, I lube the mainsprings of the lower-powered springers like a Diana 27 with the same white lithium grease.

Does it bother you that I said all spring piston guns diesel? Well, they do. Don’t confuse dieseling, which is normal and even good, with detonation — which is when you here a low bang. That’s too large an explosion for your gun, and you don’t want to do very much of it.

The barrel pivot and the forks through which it passes is another place to grease. The right grease (moly) applied here reduces the cocking effort by 10 pounds!

The mainspring is the other place that gets lubed, and often it’s to stop the vibration, though I’m going to tell you in a moment a better way to do. For this, people use black tar, or what Jim Maccari calls Velocity Tar. It’s just a very viscous grease with a high adhesion that feels tacky to the touch. Farmers and heavy equipment operators know it as open gear lubricant. Most of the different greases like this will slow your gun to some extent, but there are products like Velocity Tar which, if used sparingly, seem to not phase the velocity at all.

Remove all the play
Okay, lubricating a gun to smooth the firing cycle is a redneck approach. Many people, including me, do it that way. But there’s a more elegant way if you’re willing to work. That way is to remove all the play in the various moving parts. The piston and mainspring are the primary parts involved.

The piston in a factory gun fits well inside the spring tube, but there’s a looseness to allow for manufacturing tolerances. The piston seal takes up a lot of the slack, but it’s located just at the front of the piston. The rear is free to move in all directions. While the space is small, this is where some of the vibration comes from.

To tighten the piston, it’s possible to put small bearings at the front and rear of the piston. These are usually small, round spots of synthetic material such as Teflon or nylon. Typically, three are placed at the front and three more at the rear. They are spaced evenly around the piston body, and the front ones are offset from those in the rear. If they fit the spring tube exactly, the piston rides on them, and then a moly coating really does its work.

The next critical fit is the mainspring, and here it’s sometimes possible to buy a spring that fits the spring guide in the rear and the piston rod in the front very tightly. Tuners call this close fit being “nailed on.” When you have a close fit like this, good moly lubrication is essential, or the close fit of steel on steel will cause galling, which is a form of burnishing that causes friction, vibration and excess heat.

If you can’t find a spring that fits this tight, you can always have a custom spring guide made that does fit the spring you have. Then, inside the piston, you can put a steel shim that fits between the mainspring and the inner walls of the piston. It’ll look shoddy; but once the powerplant is together, it’ll stay in place. And moly is essential here for the mainspring and the guide. This is called a “beer can” tune, because people often use cans to make the shim.

Another trick people use is to put shims behind the mainspring on the spring guide end. This puts the mainspring under more tension and gives more power. You have to make sure there’s enough room to cock the rifle when doing this, because it’s possible to shim the spring too much.

New airgunners assume that the stronger the mainspring, the more powerful the airgun. That isn’t always the case. Piston stroke has more to do with power than the spring rating. I always look for a weaker spring because I know it won’t subtract that much power from the gun. A coating of tar will do more to slow down a gun than a weak spring, as long as the spring fits well.

A final word on the mainspring is to notice that each end is usually a different size. Try to match the end with the spring guide or piston rod that fits best.

Piston seals
Piston seals used to be a real big reason for tuning a spring gun, because they wore out or melted from friction. Today’s seals are pretty well made, though there will always be some cheapies that come to market from time to time. The thing about the piston seal is to ensure that it fits the bore of the compression tube without adding too much additional friction. Some is unavoidable, but it’s easy to go overboard. The modern parachute piston seal that expands as it compresses air is very sophisticated, and shouldn’t be too difficult to size correctly. To reduce the diameter, put the seal on the piston and rotate the piston against sandpaper. Be careful to keep the sides of the seal parallel to the compression chamber bore while doing this. It usually only takes a minute or two for this job.

The trigger can be adjusted and lubricated during a tuneup. I lubricate with moly grease, because a trigger is not a part that works by friction. No matter how low you get the friction, the trigger should always be safe…but this is a place where home tuners often have problems. They either stone or file the mating sear surfaces and put a dangerous angle on them. Then, they lubricate them with moly. These are the triggers that slip when cocked.

People are also known to adjust a trigger to have too fine mating surfaces, and once more, they’ll slip when cocked. My advice is to lube first, then let the trigger work for several hundred shots before you adjust it. I would keep stones and files away from triggers unless you’re certain that you know what you’re doing.

Breech seals
This part is often overlooked and can sometimes give you a large boost in power. The breech seal doesn’t have to stand proud of the breech to work well. It all depends on how the gun is designed. But don’t overlook the possibility of improving performance by raising the breech seal a few hundredths of an inch.

I hope this report answers most of the questions you have regarding tuning an airgun. As I said at the start, a tune can be any of these things, or all of them. A professional tune is usually all, but you should discuss the specifics with your airgunsmith before letting him start the work.

A shrine built for a Feinwerkbau 124 – Part 15

by B.B. Pelletier

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

A shrine built for a Feinwerkbau 124 – Part 14

by B.B. Pelletier

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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