Primer ignition issue: spring tension or firing pin protrusion?

[Iamero]

I have a custom 30-06 on a new haven Win 70 (post 64 with the claw extractor) and I am experience misfires. I’m using Lapua brass with CCI large rifle primers. The previous owner warned me it was doing this but he never looked into it.

It has an adjustable firing pin in there so I measured bolt protrusion to make sure it’s sitting ok. It’s currently at .070” which from my understanding is plenty far out there. Would you eliminate that and get a heavier spring or what would your next step be? I know it’s not a bad batch of primers because they work just fine in my 308 and the previous owner reported the same issues.

See pic below. Left if misfire, right is a fired round. Thoughts?

 

[buffybuster]

Clean the FP channel of all grease and lube. Double check the chamber headspace. If all that checks out, then consider a new spring.

 

[Iamero]

Yea I also wondered if the claw extractor came into play at all. I’ll have to drop it off at my smith and have him check headspace.

 

[Rust]

Some things I'm seeing are off center firing pin strikes and a little cratering on the round that fired. Cratering can be from an overly large firing pin hole, the off center primer strike can be caused by the bolt bring a loose fit in the receiver, the firing pin hole off center in the bolt, and even a bent firing pin (which could drag and cause light firing pin strikes).

Fist off disassemble the bolt, clean it completely, roll the firing pin on something very flat (a sheet of glass works) or in v-blocks with a dial indicator to check for straightness. A bent pin could drag occasionally depending o the severity of the bend, a really bent pin pretty much wouldn't work at all. Your spring looks like it gives a strong enough strike from the fired case but springs wear out and are cheap so replace it with a Wulff of the factory rating.

Another thing could be is that the chamber is a little too long. QA from the factories isn't always perfect and a go/no go gauge set will easily determine that. Any smith who doesn't have -06 gauges.....

If all of that checks out and there is still an issue, see a good smith. Those off center strikes could be (but not too likely) the problem. Off center strikes are caused by the firing pin hole not centered in the bolt (relatively easy fix) or a loose fit of the bolt in the receiver (not so easy fix).

Of course all of that assumes your primers aren't seated too deeply.

 

[Iamero]

I’m going to drop it off at my Smith this afternoon and have him check some of those things out, I appreciate the heads up on some things to look out for. The primers did see like they were seated a little deep in the case, but I thought that would be weird that was consistent between myself and the previous owner. Also, my protrusion is farther out than most bolt rifles already so that should make up for overseated primers.

 

[ShtrRdy]

Something else to measure is the Firing Pin Fall. How long of a run does the Firing Pin move before contacting the primer.

 

[Iamero]

We polished everything up and the firing pin appears to be straight (so the offcenter hits are possibly a misaligned hole). We check the headspace and that was all good, maybe even a little snug. I’m ordering a 30lb spring from Wolff to see if that will help.