What would cause the primer caps to come off and cause a failure to eject? Rifle was cleaned and lubed before shooting. I ran a few hundred precision one .223 55 grain without issue, one box of Remington match .223, one box of hornday .223, and a few boxes of aac 55gr 556. Only problems with aac 77grain ammo. A few fail to fire which looking back seemed to be a light primer strike. I tossed rounds in the can at the range instead of taking picture. Also had a primer seemed to wedge itself in the breech next to the case of one round. Could this have been an improper cleaning method or any other user error?
if those were reloads I would say over pressure or worn cases. If those are factory loads, then I don’t know what else could cause an over pressure which is the typical reason primers blow out.
got any pics of the bolt face? if over pressure caused this, I would get that rifle inspected by a good gunsmith to make sure there are no cracks.
the way those bases are blasted out, I would take a very long look at the bolt. Not the BCG but the bolt face . Take the bolt apart and give it a good check over.
also wondering, is your rifle chambered .223 or 5.56.
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Factory loads
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556
I’m going to ASSume the light strike/failure to fires occurred after the blown primers. If you pull the firing pin out of the bolt you’ll probably find primer shrapnel in there. This will keep the firing pin from traveling all the way forward.
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Yes, but it only seemed to happen with the 77gr 556.
There was some trash that came out.
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The one on the far left appears to be the most over-pressured.
That is an alarming amount of variability.
The goal of the production line is to make them all uniform.
I cropped it and adjusted levels to make the pressure mark geometry appear to jump out.
I really appreciate your showing your results.
AAC needs to address the situation, e.g. do a recall and get busy measuring and analyzing.
5.56 cases don’t over-pressure randomly, though they may appear to.
Of course from the AAC factory point of view, it is reasonable to ask, considering the overall system - is there anything on the firearm that is related to the over-pressure ? specifically what is the shape of the chamber.
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I have a few more boxes of this that I may shoot tomorrow along with regular 55gr 556. I’ll keep the boxes and any spent casings along with any fail to fire rounds.
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How true is the bullet supposed to be in the case? I just opened a new box and notice some of the bullets seem “off” or tilted. When rolling them it’s like a bad pool Q.
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Which ones are you using I just rolled 10 random out of a box of AAC Sierra 77 and all rolled true.
if you take your BCG out and then insert a cartridge into the firing chamber, does it seat easily? I’m wondering if the bolt isn’t fully closing and locking before discharge.
Ran the last 2 boxes today with no issues. Checked over each round before using.
What is your barrel length? Is it suppressed?
16”
No
Without having been there and witnessing it, I can only attribute this to a batch of bad ammo. Is there any batch information on the boxes? Wondering if they are different.
That’s what I’m thinking. No, of course I tossed them.
I’ll pay more attention in the future though.
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One alternative.
I have less & less time for re-loading. So I’ve been looking for alternatives in the 75/77 grain category.
I also bought a box of the AAC in the process of rounding up the alternatives.
PPU also makes a 75 grain 5.56/223.