I thought at first it might be a weak spring so I changed the firing pin spring out with a J&P heavy duty unit and I'm still experiencing misfires.

I've dissassembled the bolt and scrubbed out the inside to make sure nothing was holding it off the rim. I also took a little emory cloth and polished up the firing pin stop area just in case something unseen was causing this problem.

You can see strikes on the case rims but there are light.

I'm at witts end here.

Any suggestions?

Terry

firing pin


case

Rimfires requires a solid hammer and anvil to fire. With the heavy spring, it sounds like the hammer portion is taken care of, now look at the anvil. The mouth of the camber has to firmly support the rim of the case in order for the pin to penetrate the rim. The rim mustn't give under the force of the strike.

I have a High Standard "Problematic" currently on the bench that is getting an new rim insert because the original surface has been beat and ironed to the point that it can no longer support a pin strike.

While you are at it, I would stone the pin just enough to redefine the edges. When you are working to penetrate a hard rim, sharp, clean edges penetrate better than dull, rounded ones.

Thank you.

Terry

Excess headspace or short protrusion could cause light dents as well. The thing with protrusion is to not have it long enough to whack the chamber causing problems like Westpac posted.