How to maintain a PCP airgun
by B.B. Pelletier
This report was requested several months ago, but I needed time to consider it before writing. Maintenance is such a subjective thing. One person just wants to keep his airgun running like new, while another wants to see every screw and seal in the gun. I think that goes beyond maintenance, so I will confine this report to people who just want to care for their gun to keep them shooting as long as possible.
1. Keep your airgun under pressure!
Letting a PCP go empty is always risky, because the ambient air can then get through the valve and into the gun. Ambient (room) air is full of dust, small dirt particles and droplets of harmful things, such as water and solvents (if you clean firearms nearby). Keeping a gun or separate reservoir pressurized keeps the door shut against these harmful things and here is some proof.
I have a DayState Harrier that has been holding air continuously since 1999. But I let the air out of a Career 707 that had held for six years, and it developed a leak. I have several other PCPs that have held air for nearly as long as my Harrier, but many guns that have had the air released have had to be rebuilt before they held again. The seals were not bad in most cases. They were just dirty!
2. Use high-grade silicone lubricants!
These lubricants cost more money than easily available hardware-store lubes,. They're more difficult to find, but a PCP needs them to operate. They are NOT for lubrication, but for sealing! Regular petroleum-based lubes are used for true lubrication, but put your oil cans away. The amount of oil and grease a PCP needs is very small. In the eight years I've owned my Harrier, it's never been lubricated. Period! It still doesn't need anything.
AirForce guns need silicone lube on the large o-ring that seals the tank to the adapter. I do that about once a year, regardless of the number of times I fill the gun. The double o-rings on the fill probe of a quick-disconnect need more frequent lubrication, and frequent cleaning. Because these o-rings are exposed to the air, they pick up dirt, which the lube on their surfaces holds. I either store my probes in a plastic bag, or I clean and lube them before every use.
Exposed o-rings on this fill probe should either be covered when not in use or cleaned before each use. They need a thin coat of silicone grease on them before being inserted into the fill port.
3. Get a chronograph!
PCPs change velocity over time, and it takes a chronograph to properly adjust them again. For example, Falcon rifles will start out at one speed when new, then climb by 30-40 f.p.s. after about 500 shots. It's just the way they settle in. With a chronograph, you can watch for this and adjust your gun when it happens.
4. Do you need to lube pellets?
If you shoot pure lead pellets below 900 f.p.s., you probably don't need to lubricate them; it would depend on how smooth your barrel is. If you shoot Crosman Premiers at 900 or faster, then you should lube them in some oil before shooting. Otherwise, you will have to clean the barrel periodically. A PCP is a dry gun, where a springer blows a small amount of oil from the compression chamber into the barrel with every shot. Lead has its own lubricity, but above about 900 f.p.s. it needs help.
5. How often should you clean the barrel?
Clean the barrel as seldom as possible. Only clean when there is an accuracy problem, and then scrub the bore with JB Non-Embedding Bore Cleaning Compound. My Harrier has never been cleaned, and it still shoots well.
Five JSBs at 35 yards from my Harrier show that 10 years of not cleaning the barrel is no problem. Group measures 0.170" c-t-c.
Are there more tips? Of course! Here's one. Don't take your rifle apart! These are not just PCP tips, they apply to cars, wristwatches and to life in general.