Airgun lubrication — spring guns: Part 2
by Tom Gaylord, a.k.a. B.B. Pelletier
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.
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.
“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.
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.
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.