Help diagnosing failure to fire?

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Weetabix
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Help diagnosing failure to fire?

Post by Weetabix »

I bought a Bear Creek Arsenal 7.62x39 upper to shoot for grins. Seller said he'd never had a problem. But everyone says that.

Took it out to shoot, and in a box of 20, I think I had 7 rounds fire. The rest... no joy. This was with 2 different lowers. Ammo was Golden Tiger, which I'd read good things about. Only had the one kind of ammo, and only had the one upper - nothing else to try the ammo in.

At first, I thought maybe it was a hard primer/light strike problem, but if you look at the primers, the one that failed to fire (B) looks like it's a good, deep strike and the primer looks concave rather than flat like the one that fired (A). I've never seen that before. Anyone else seen that?

I'm thinking I need to try different ammo in the upper and try the GT in an SKS to see if I can eliminate some variables.

ETA: a coworker noticed that the primer in B is set deeper than the primer in A. I also need to look at some of the unstruck rounds in the can.
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Last edited by Weetabix on Mon Nov 06, 2017 4:36 pm, edited 1 time in total.
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Vonz90
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Re: Help diagnosing failure to fire?

Post by Vonz90 »

Weetabix wrote:I bought a Bear Creek Arsenal 7.62x39 upper to shoot for grins. Seller said he'd never had a problem. But everyone says that.

Took it out to shoot, and in a box of 20, I think I had 7 rounds fire. The rest... no joy. This was with 2 different lowers. Ammo was Golden Tiger, which I'd read good things about. Only had the one kind of ammo, and only had the one upper - nothing else to try the ammo in.

At first, I thought maybe it was a hard primer/light strike problem, but if you look at the primers, the one that failed to fire (B) looks like it's a good, deep strike and the primer looks concave rather than flat like the one that fired (A). I've never seen that before. Anyone else seen that?

I'm thinking I need to try different ammo in the upper and try the GT in an SKS to see if I can eliminate some variables.
I agree with your plan. Switch ammo and switch guns. If the failure follows the ammo, it is the ammo. If it follows the gun, it is the gun.
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Weetabix
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Re: Help diagnosing failure to fire?

Post by Weetabix »

I guess I forgot to emphasize: The strike in B looks deep enough, but the way the primer looks concave makes me wonder if this ammo might blow up in my face. Is that a valid worry? I've never noticed that before, but I seldom scrutinize my brass for that.
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Netpackrat
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Re: Help diagnosing failure to fire?

Post by Netpackrat »

The Golden Tiger ammo has hard primers and is meant for AKs, and has been known to give failures to fire in AR rifles. There is an enhanced firing pin you can install which is supposed to cure the problem. GT is probably the best of the steel case Russian ammo, and the closest thing to the original mil-spec 7.62x39 that we can get here in the US. The issue is more of an incompatibility than a problem with either rifle or ammunition.
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rightisright
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Re: Help diagnosing failure to fire?

Post by rightisright »

Yeah, try it in a com-gun. I really like the Golden Tiger in my AKs and SKSs. Never a dud and cleaner than most steel cased.
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slowpoke
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Re: Help diagnosing failure to fire?

Post by slowpoke »

Is that a berdan primer in a boxer case?
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Netpackrat
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Re: Help diagnosing failure to fire?

Post by Netpackrat »

I like the GT 7.62x39 enough that it is all I am buying for steel case these days. Once the last of my Wolf is gone the GT will be my default training ammo. It seems to group a little more consistently, and prints several inches higher at 100 than the Wolf. It uses a boat tail bullet, so it should have less drop at range, and unlike Wolf, it still has sealant on the bullets and primers.
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Jered
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Re: Help diagnosing failure to fire?

Post by Jered »

Wear safety glasses and you should be pretty safe. If ammo isn't in a gun, it won't even go through drywall.

Could it be a bad batch of primers in that lot of ammo?
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Netpackrat
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Re: Help diagnosing failure to fire?

Post by Netpackrat »

There is nothing wrong with that ammo; it is just not made for use in AR-15 rifles. If you want to use it you will need to install an enhanced firing pin.

http://www.blackriflearms.com/AR-762x39 ... n_p_9.html
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Jered
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Re: Help diagnosing failure to fire?

Post by Jered »

I wasn't speculating about the brand of ammo.

I was speculating that that particular manufacturing lot of ammo could have gotten a bad batch of primers.

Can you pull the bullets out?
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