7.62×51 Ammo issues.
I recently finished my EBR build off an M1a Socom. In preparation, I bought 500 rounds of Winchester 7.62 ammunition to shoot after it was ready. At the range, I experienced several light strikes/misfires. I made a mod to the trigger and figured I had messed something up so I brought it to my gunsmith. He checked it out, didn't see any issues and attempted to fire my 7.62 ammunition with it with a high failure rate. When he used his 308. Ammunition, he had no issues whatsoever. Can anyone explain this to me? Has anyone had a similar issue firing 7.62×51? Any advice would be tremendously helpful.
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I'm of the belief the Winchester White box 7.62 is a bit to hot for the M1-A platform
I have had no problems with WWB 7.62x51 nato. maybe something in your trigger group.
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Previous thread that has the protrusion specs. That would be my first check.
FP Protrusion
edit: I'm assuming you or your gunsmith checked headspace. My next advice would be to make sure the bolt is rotating fully into battery on the ball ammo. If you have a tight chamber (near min spec) and ammo near max you could see the bolt not rotate all the way home and subsequent firing pin drag.
FP Protrusion
edit: I'm assuming you or your gunsmith checked headspace. My next advice would be to make sure the bolt is rotating fully into battery on the ball ammo. If you have a tight chamber (near min spec) and ammo near max you could see the bolt not rotate all the way home and subsequent firing pin drag.
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3,338 Posts
Was it visually VERIFIED that the bolt had rotated completely closed for each shot? If not, then try that FIRST.
How does the firing pin indent on the primers look - especially comparing the ones that did fire to those that didn't.
If FP protrusion is OK and indent looks marginal, then replacing the hammer spring with a known good one might help.
How does the firing pin indent on the primers look - especially comparing the ones that did fire to those that didn't.
If FP protrusion is OK and indent looks marginal, then replacing the hammer spring with a known good one might help.
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When looking at the bolt, the firing pin protrusion doesn't seem adequate (I am fairly inexperienced). What factors are involved with that? Is that something I can do/adjust or is that pretty technical?
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You guys are awesome, thanks for all the replies. I'm going to to some research to try and get to the bottom of this. A mistake I made was buying the rifle brand new, and outfitting all my mods on it before firing. It would have been nice to know if any of the work I did is preventing it from working with this particular ammo.
The ammo that fires seems to have a much more significant primer strike. The soft strikes, are a much weaker indentation. What would cause that inconsistency?
I had similar issues due to myself grounding one hammer spring coil off to reduce trigger pull. Suggestion: add a shim under spring to increase hammer pressure(if you can). Yeah.... It sucks but after I reinstalled a NEW spring, my issues went away. In my opinion, trigger pressure is this rifle's weakest link.
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There is the best suggestion yet. New rifle could have all sorts of crap within the bolt. When folks say it is important to take a new rifle apart, clean and lube before use, it is not a joke and that includes disassembling bolt, gas cylinder. rear sight and trigger group.
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331 Posts
When did you purchase the ammo, and more importantly when was it manufactured? During these ammo crunches quality goes down big time, even with "premium" SD/Duty ammo. I would try at least three other manufacturers M80 ball ammo.
Checking the bolt will cost you nothing and good place to start and then checking for defective out of spec parts like the firing pin.
Checking the bolt will cost you nothing and good place to start and then checking for defective out of spec parts like the firing pin.
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6 Posts
I just purchased a bolt diss/ass tool from Fulton. The firing pin seems a bit sticky, and I don't know what good firing pin protrusion looks like, but it seems like my firing pin barely sticks out of the bolt when forward. I plan on taking the bolt apart to see if there is anything causing issues. Thanks for the reply.
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told ya ima not as dumb as i look
Had a similar problem when I first got my rifle; mine was because of over lubrication. What I had used got on the firing pin somehow and caused sporadic operation. Everyone else's ideas may sure work, but try the cheapest solution first; blast out that firing pin channel with some gun scrubber/brake clean, lightly apply oil to the metal surfaces and wipe off the excess, lightly grease the heavy metal on metal wear parts of the bolt and the roller, and give it another try with bare minimum lubricants. If you're new to M1A/M14 like I was/am, it's entirely possible you just over lubricated.
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So right now I have a bolt assembly device on order because I have a gut feeling that there is an issue with the firing pin. My plan right now is to break it down and clean it out. It feels like there is some friction/ sticking within the bolt. And I am new, this is my 1st M1A rifle. Thanks for the advce.
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That is definitely my biggest mistake so far. I took the factory M1A, and put all my upgrades on it all at once. Even my gunsmith kinda shamed me when I brought him my upgraded rifle. A lot of stuff I didn't realize was important. Hind sight.
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1,153 Posts
With the assembled bolt out of the receiver, the firing pin should be loose and move freely front to back. If it does not, do not fire the rifle until the firing pin issue is resolved.
Just because someone gets referred to as a "Gunsmith" does not make it so, and it does not mean they are familiar with M1 Garand and M14 type rifles.
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Most so called "gunsmiths" are just machinists that like to work on guns, very few have had formal training in a classroom on the mechanics of various firearms and how to make them function correctly. If you want to test a guy to see if he has had some kind of formal gunsmith training, ask him what the cycle of operation is for your rifle, if he gives you a blank stare then go find a real gunsmith.
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