The importance of seals in airguns
by Tom Gaylord
Writing as B.B. Pelletier
This report covers:
- What is so important?
- NRA Show sample gun
- Breakbarrel breech seals
- Pneumatics and CO2 guns
Today’s report was supposed to be about the accuracy of the Umarex Synergis rifle from 25 yards. Sorry, folks, but this other topic came up and I HAD to do it today. Brother-in-law, Bob, don’t fret. Tomorrow! And, Jungle Shooter, Friday was supposed to be about the accuracy of the Artemis pistol at 25 yards. Monday, for sure.
What is so important?
Let me tell you a little story. A couple days ago I purchased a nearly new-in-the-box IZH 46M target pistol. I know! Stop salivating! I will sell it when I’m finished with it. I had planned to do a comparison review for you between the regular 46 and the 46M that is the later more powerful magnum version of the same gun. But when I chronographed this new gun it was only shooting 250-300 f.p.s. It’s supposed to be up around 500 f.p.s. with light lead pellets, while the regular 46 goes about 425 f.p.s. with the same lightweight pellets.
NRA Show sample gun
The new gun had been a sample at one of the NRA shows held annually around the nation. It is complete and looks like it has not been shot or even handled much. Then I looked at the breech that raises up when the gun is cocked. It moves up and back to give room to load the pellet into the back of the barrel. There are supposed to be two seals on this part and one of them was missing. Fortunately the Russians supply the guns with the seals for a rebuild, so I installed a new breech seal. Next shot with the same 7-grain pellet went out at 475 f.p.s. Not bad for an airgun that has probably been sitting around untouched for 18-20 years! That’s a gain of 175 f.p.s. for the installation of one breech seal.
I even have a “secret” method of bumping up the velocity of these SSP airguns and I will do that with both pistols when I test them for you. And yes, of course I will show you how it’s done. I did it on year one (2010) of “American Airgunner” but they don’t rerun those older episodes, do they?
That got me thinking. What other things do airgun seals do when they go bad? And that caused my imagination to explode! That’s why I’m writing this short report today — as an introduction to an equally short video on the importance of seals for airguns.
Breakbarrel breech seals
I thought of the breech seals in many breakbarrel rifles and pistols. A lot of them are just o-rings that to the uninitiated may look fine, and yet they can rob the gun of significant power.
An o-ring can look fine and still be bad. Many o-ring materials dry out over time and become hard. In the breech of the breakbarrel they may flatten a bit and allow air to rush past them instead of going up the barrel behind the pellet. I have seen instances where as much as 20 percent of the gun’s velocity is lost through a faulty breech seal. The best solution is to replace the seal. You can also shim an older one and get by for a little while.
Pneumatics and CO2 guns
Here is the most dramatic case of all — old seals in a pneumatic or a CO2 gun. In the past 4 years I have FIXED about 90 percent of the airguns I have treated with Automatic Transmission Stop Leak. Not just made better — FIXED!
I had to share this with you today, and to do that I made a short video. You may want to expand the video to full screen to see the details.
If you buy or acquire older airguns, and even guns that are new and have never been used but are still older, you need to consider the condition of their seals. The mechanical parts of the gun may function as they were designed, but if the seals have dried out, taken a set or are even missing, the airgun may not function well.