Help diagnosing multiple issues today

[Wake27]

I was having a few different issues with one of my ARs today while shooting groups at 50m. The first was that the trigger wouldn’t move, almost like the gun was on safe. I’ve had a popped primer get under there before and this felt very similar to what I remember of that, so between that and how dirty my lower is, I assume that’s the cause of that issue. The next though, I’m not sure of. There were two-three times where I’d pull the trigger, and it’d break, but the round didn’t fire. I took a look and couldn’t see any sign of a primer strike. The lower is filthy but the upper is not, so I wouldn’t expect that there is gunk in the firing pin channel. I also had a round get stuck in the chamber that I had to mortar to get out. That was new Hornady Black 75gr ammo so I wouldn’t expect it to be the problem. Finally, there was one-two feed issues but I don’t really remember the specifics because I have a habit of just tap racking and going, instead of diagnosing the problem.

I don’t know what ammo the other problems happened with, but all of it was some type of OTM and the cheapest was 75gr PPU.

If anyone has any insight on the non-existent primer strikes and the stuck round, I’d appreciate it. I just included the other stuff for more info, though I haven’t yet confirmed that there is an obstruction under my trigger so that one could still be a mystery as well. I’d rather not mention the manufacturers so that I can reach out to them first, if it is deemed that some of this could be issues with at least part of the gun.


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[ALCOAR]

What are the specs on the rifle in question?

The trigger not moving sounds almost assurdly to be a popped primer obstructing movement. It also could be the reason why you had the trigger fall, but no indented primer marks on the brass.

[P2000]

A few years back I was shooting some CBC 62gr in my SPR. Its chamber is darn near minimum headspacing. CBC was defective and some rounds were over max. That caused failure to fire followed by having difficult extraction and sometimes having to mortar the unfired round out. Had to stop shooting the CBC in the SPR.

Not sure if this is what happened in your case, but something to think about if you get a failure to fire followed by difficult extraction.

[Wake27]

What are the specs on the rifle in question?

The trigger not moving sounds almost assurdly to be a popped primer obstructing movement. It also could be the reason why you had the trigger fall, but no indented primer marks on the brass.

The primer stopping up my trigger happened three years ago so it’s hard to say for sure, but it definitely felt similar from what I remember. I know that was the case then because I was at a RB1 class asked Jason what was going on. Sure enough, we shotgunned the rifle and pulled out a primer.

As far as specs, the lower is a Noveske that came with an SD-E installed. It’s seen three different primary uppers as well as some others every now and then so I don’t have a close round count but it’d be between 6-8k with very little having been changed in a lot of that time. I did put the A5 system on years ago. Not sure what the life is like for the green spring that’s in there but I did swap between an A5-2 and A5-3 and still had at least one of the malfunctions.

The upper was brand new, I shot it for the first time today. Part of me wondered if it was just break-in, even though that’s not supposed to be a thing. Eventually I did swap it to another lower and didn’t have any more problems. Round count was maybe 40-50 on the Noveske lower and then at least that many on my backup Aero lower.

A few years back I was shooting some CBC 62gr in my SPR. Its chamber is darn near minimum headspacing. CBC was defective and some rounds were over max. That caused failure to fire followed by having difficult extraction and sometimes having to mortar the unfired round out. Had to stop shooting the CBC in the SPR.

Not sure if this is what happened in your case, but something to think about if you get a failure to fire followed by difficult extraction.

I think I fired seven different rounds through it. Once it had an issue with more than one, I stopped paying attention to what ammo was causing problems. Rounds from all of the same boxes were fired out of the same lower two weeks ago and between three different uppers without issue.


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[lysander]

Have you cleaned and inspected the parts?

[gaijin]

Is the Hornady ammo to spec, verified COAL not over max?
Could have a short leade?

I’d be cleaning and inspecting as above.

[Iraqgunz]

This is hard to actually diagnose, since you cleared some issues and moved on and then swapped stuff around. You need to go back to ground zero and start over. I will tell you that I have had issues with PPU 75gr. ammo in the past. It was blowing primers quite frequently. I think it was due to the primers not being staked right, and not due to pressure.

I would put everything back to zero, and then start with quality known ammo that you know 100% works without issue.

[Wake27]

Sure enough, lodged under the hammer spring.



I haven’t seen anything on inspecting, but did notice when I first got it that the bolt doesn’t easily return to battery when hand cycling. I didn’t think much of it since that was just by hand, but it’s still doing it now and I’m wondering if maybe there’s a bur in there somewhere or something else is going on between the bolt and barrel extension.


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[Wake27]

Is the Hornady ammo to spec, verified COAL not over max?
Could have a short leade?

I’d be cleaning and inspecting as above.

No idea, I only had four rounds. That ammo was used by someone else to test my other upper’s accuracy so I just had what was left over from the box.

This is hard to actually diagnose, since you cleared some issues and moved on and then swapped stuff around. You need to go back to ground zero and start over. I will tell you that I have had issues with PPU 75gr. ammo in the past. It was blowing primers quite frequently. I think it was due to the primers not being staked right, and not due to pressure.

I would put everything back to zero, and then start with quality known ammo that you know 100% works without issue.

The more I’ve grouped the stuff, the less impressive it’s been. That being said, this was a 1k round case and I’m down to maybe three hundred rounds and have never noticed a problem before, though not sure I would have. That being said, I assume blown primers would be 100% ammo related right?


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[Clint]

Not returning to battery would explain the no-fires.