What to oil – Part 2 Oiling piston and breech seals
by B.B. Pelletier
I will be gone next Monday through Thursday. I’m going big bore airgun hunting on an exotic game range here in Texas. I’m asking you veteran readers to cover me on the comments during that period. Next Friday, I’ll reveal a big new product for you. It should be worth the wait.
I had completely forgotten about this series, but Stingray reminded me on Wednesday, so here’s the next part of the lube story. This is a really important report, because much of airgun operation and efficiency depends on the right lubrication and I’m glad to record it in one place.
Before I begin, we have a new reader who has just purchased what he believes to be an unfired Beeman R1 rifle in .20 caliber. I invited him to come to this blog and promised to answer his questions about keeping his new rifle in top working condition. This report on lubrication will go a long way toward that goal.
Today, I’m going to discuss how to oil the piston seal and breech seal on spring-piston guns including breakbarrels, sidelevers and underlevers.
Different oiling categories
Spring-piston guns must be divided into several categories before a lubrication plan is put into practice. I’m not talking about how the gun is cocked (breakbarrel, sidelever, underlever or any other method) but how the powerplant is constructed. The age of the gun plays a large part in making the lubrication schedule, so let’s begin there.
If you absolutely cannot find the air transfer port, you can drop the oil directly down the muzzle with the gun standing upright. On most guns, the oil will flow straight through the barrel to the transfer port. Only a few, like the IZH 61, have a transfer port located 90 degrees to the axis on the bore.
Some airguns are bound to have leather seals, and the older they are the more likely leather becomes. Leather piston and breech seals need lots of frequent oiling. Many of the older guns are also lower-powered, so the oil can be petroleum-based, if you like. For a gun with a leather piston seal, I would oil the seal every time you shoot the gun if you only shoot it occasionally, or once every two weeks if you shoot all the time. Drop 5-10 drops of oil down the air transfer port and allow it time to soak into the leather. Then cock and uncock the gun without firing, if you can, to make the seal flexible. Often, you can hear the seal go squish when you do this.
At the same time, if the gun has a leather breech seal, drop two drops of oil on the seal and allow it to soak in. If the seal is synthetic, it doesn’t need any oil. It will be oiled by the small amount of oil that’s blown from the transfer port as the gun is fired.
That dark circle around the bore is a leather breech seal! It doesn’t look very good (kinda flat), but with frequent oiling it still works after 40 years!
Guns with synthetic seals require far less lubrication. The best of them are the RWS Diana rifles whose piston seals are nearly self-lubricating. The worst are possibly the cheaper Chinese guns whose seals are made from softer synthetic and may need more lube to do their job. I’m talking about guns like the B3-1, not a Beeman gun made in China. On average, a single drop of silicone chamber oil every 1,500 shots or once a year is about all they require. You can double that time for RWS Diana guns. The oil goes down the transfer port, the same as for guns with leather seals.
Unique seals and special circumstances
Some target springers, like the FWB 65/80/90, have piston rings that require oil infrequently. Follow the owner’s manual for these guns. Other target guns, such as the Diana model 6 and 10 pistols and the model 60, 65, 66 and 75 rifles, have synthetic seals that require very little oil. Older guns, such as the Webley Senior which are pre-WW II, have a beryllium-copper piston ring that needs more oil. A couple drops every month or every time you shoot the gun will do. These older Webleys also have a fiber washer that serves as a breech seal. Oil them like leather breech seals.
Another special circumstance is a gun that’s been lubricated in such a way that it lasts for many years without any extra lubrication. When I lubed my Diana 27, I loaded the mainspring with white lithium grease. It continually wicks into the piston seal and keeps it lubed, and that’s been happening for about a decade now. When I tune a gun with synthetic seals, I coat the compression chamber and seal with moly grease. A gun will last 5 years lubricated that way–maybe less with hard use. So take the advice the airgunsmith gives you when he tunes your springer.
There’s a final special circumstance I need to describe for you. Some spring guns made in the 1970s–like the FWB 124, Walther target rifles and Diana target rifles and pistols, have a poor formulation for the synthetic piston seal. The piston seals in these guns can dissolve in minutes when they’re oiled for the first time after a long dry spell. The symptoms are that the gun won’t shoot a pellet out the barrel, and you’ll find chunks of a dark yellow waxy substance in the barrel when they’re fired. Those are parts of the disintegrated piston seal. Stop shooting and replace the seals immediately. The new seals you use will not do that.
Beware of older information
Beware of reading the older airgun catalogs. They contain instructions for more frequent oiling of synthetic piston seals because people were not yet accustomed to the longer intervals they really require. Consequently, they tell you to oil every 500 pellets and to use three drops or more, which is way too much for a synthetic seal.
I have purposely not covered any other lubrication for spring guns. That subject will get its own report, next.