I have seen firing pins fail to detonate because some idiot used a home brew lube and it was a bit above freezing.
You could take the bolt out, set it face down and drop the firing pin into it and it would not slide down to the collar.
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I have seen firing pins fail to detonate because some idiot used a home brew lube and it was a bit above freezing.
You could take the bolt out, set it face down and drop the firing pin into it and it would not slide down to the collar.
The first thing I would check is firing pin protrusion.
The firing pin protrudes out of the extractor just fine as far as I can see. If I remove the retaining pin, the firing pin slides back and forth just by tilting.
I'll try upgrading the springs and go from there.
I doubt the BCG is the issue, it is a BCM after all.
I had a similar problem with a 6.8spc. The fault was out-of-spec factory ammo: the necks were oversized. Slightly oversized (.307 versus .306) usually still chambered, and I saved the remaining few boxes for practice. More oversized (.308) I returned for refund.
Have you cleaned it? I had the same issue when the firing pin on mt carbine had built-up so much carbon at the front of the "hat" it prevented enough of the firing pin to contact the primers. It also would not hurt to clean the inside of your BCG.
ADDED: Have you experienced similar issues with other ammo makers? if so, then your hammer spring is probably the culprit.
Good luck!!
Firing pin protrusion gauging is a little more detailed than just seeing if the firing pin passes through the bolt or not.
It is a measurable max/min requirement to ensure that the firing pin protrudes sufficiently from the bolt face to ensure that the firing pin sufficiently dents the primer without piercing it. Now I am not saying that this is the issue, but it could easily be a tolerance stacking issue between your firing pin protrusion, headspace, primer height and anvil depth. All it takes a little bit of error here and there and you get unreliable ignition.
The reason that I say that the first thing I would check is firing pin protrusion is that it is really easy to swap a firing pin or bolt and keep on shooting. I doubt that it is a hammer spring or obstruction issue if it is only happening with PMC.
Point taken, however, considering the upper assembly, bolt, bolt carrier, firing pin, and CH are all Bravo Co. I doubt it would have left the factory if it was out of spec.
Also, as I inspected the rounds, the primers on the PMC were dimpled more than the primers on the Winchester Q3131A1 that fire every time.
did you happen to re-try any of the "bad" rounds in your gun before you let your buddy try them in his?
You know, I did not.
Honestly, if I wasn't so anal retentive about how my shit works I would just pull the charging handle and move on with it. What is really weird, is I have shot PMC before. I bought a few boxes from Big5 once and those all shot fine.
I just double checked the springs and they are all installed properly.
I'm beginning to think my RRA lower parts kit sucks. I know for sure I need KNS pins, the trigger pin loves to walk out after only a dozen or so rounds. I think I will get a set of those and the better springs from brownells and be done with.
The feedback has been great.