Canadian Airgun Forum

Ok guys i have been re-building my RM422 for quite some time. Since parts can not be aquired for it anymore I have been busy as a beaver finding parts from other rifles that will fit. So far I have installed a Quest spring that works really well. And Sniper told me the Diana 24 piston seal will fit.

So here's the deal. With the Quest spring and the original piston seal since i don't have a chrony I have to compare it to other my other rifles that I know the velocity of. Well by the looks of it my RM422 is getting just to 500fps or little bit over. I was lucky and out of the box before it broke down I was getting quite a bit over 500fps. Well I got around to installing a diana 24 piston seal and after I isntalled it my RM422 wouldn't shoot worth litter!. I could see the pellet flying through the air. So me being really angry I took the Diana seal out and put the origianl RM422 seal back in and it was like night and day between the 2.

But here is the problem the original piston seal is scratched and worn so it doesn't make a perfect seal. But the Diana 24 piston seal makes a pefect seal so how come it makes my RM422 shoot so slow? does it need a break in period like most piston seals? What should I do? This is my favourite airgun in my collection I would like get it shooting perfect again. Any ideas or advice? Thanks. Sorry for the very long post.

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ONE SHOT, ONE KILL

I will hazzard a guess By perfect fit I assume that you are saying that no air is escaping past it. Could it be to tight, as in, tight enough to slow the speed at which the piston travels when the trigger is pulled?

Perhaps try squeezing the seal smaller with a hose clamp over night to see if that makes a difference.

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When I say perfect I mean it's actually just perfect not to big not too small. If it were to be sqeezed smaller over night it would be too small then. so I really don't know what to do.

Edit: Also the seal is made of a softer material and cones out so when the trigger is pulled and the piston travels down the tube that means the sides spread apart making an even tighter seal so maybe you are right it could be a little too tight fitting inside the compression tube.

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ONE SHOT, ONE KILL