Dead AR Trigger due to Blown Primers.

[Wake27]

I’ve seen this, and had it happen. As @Wake27 posted, most of the stoppages are fixable with a tool. This is one reason I prefer open triggers over drop in modules.

Hornady brass sucks, but I’ve never seen blown primers in quality factory ammo unless something else was going on. Wet ammo can cause high pressures, and blow primers.

Yeah so the first time I had this issue, I was shooting Freedom Munitions factory reloads that were bought during the post-Sandy Hook era. Could have just been the trash ammo. But, that upper (Noveske) ended up having some other issues that may or may not have contributed.

The more recent experience has been over the last few months with a Criterion Core barreled upper shooting mostly MEN 56gr 5.56, which is good ammo. Lots of back and forth and trouble shooting to the point that Criterion re-barreled my upper and I just got it back a few days ago.

Long story short and in agreement with CF, if you have reasonably decent factory brass ammo and it’s happened more than once, there’s something else going on.


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[Shawn Dodson]

One more reason NOT to install anti-rotation pins because they require a tool to remove, whereas standard pins can be pushed out with the tip of a cartridge.

[ST911]

Would a cassette style trigger prevent this?

In my experience, no. But cassette triggers make it harder to clear.

Does not prevent, can complicate if you have primer fragments.

[BK14]

We were having issues with a lot of ammo that was blowing primers, 55gr tap. I had a primer get stuck under my trigger while doing a qual with the tap ammo. ALG trigger, non-lubed lower. Quick pop of the pins to loosen the trigger components and the primer was out.

Confirmation on testing your ammo, using standard non-trigger pack triggers, and standard pins.

[dmiculek]

I seem to remember that at one time someone offered a "receiver rug" that was supposed to catch a blown primer or other debris from getting into the trigger area. Not sure if they are still around or if it would work as intended.

[DDTSGM]

You mean this thing?



https://www.midwayusa.com/product/1003349235

General consensus at the time was it was a gimmick and could cause more problems than it helped.

[JohnO]

Adding the following.

There was someone at the training event who told my friend that his gun was overgassed and that caused the primers to blow out. The advice included a recommendation of modifying the gun either with an adjustable gas block or an adjustable bolt carrier. I stayed out of that conversation. Later my friend contacted me and asked what I thought he should do.

I started with "don't monkey with the gun! Two blown primers do not equal a gun in need of modification/gas regulation." I told him you don't throw the baby out with the bathwater without knowing the actual cause.

My friend told me he went online and found only positive reviews of the Norma 62 gn. ammo he was using. I told him the typical guy writing a review is no different than the typical gun owner. They don't shoot enough to have a worthwhile opinion!

We are both attending a high round count carbine class next month, he doesn't want the gun going down like that again. My friend has decided he is going to the class with a different upper, a 13.7" pinned & welded to 16".

[WobblyPossum]

If he brings the same ammo, that will help diagnose whether it’s really his upper or that specific lot of ammunition.

[dmiculek]

You mean this thing?



https://www.midwayusa.com/product/1003349235

General consensus at the time was it was a gimmick and could cause more problems than it helped.

Could be, reading the thread I remembered reading about it sometime in the past.

[ST911]

There was someone at the training event who told my friend that his gun was overgassed and that caused the primers to blow out. The advice included a recommendation of modifying the gun either with an adjustable gas block or an adjustable bolt carrier.

No.

We are both attending a high round count carbine class next month, he doesn't want the gun going down like that again. My friend has decided he is going to the class with a different upper, a 13.7" pinned & welded to 16".

The BCM KD4 upper is GTG, my dollar is on ammo itself or a compatibility quirk. Try the ammo in a different gun and see where the problem moves.

Adding 'cause it occurs to me, not specific to OP's issue...

We say "blown primers" in conversations like these, but that's not the correct or best descriptor. Summarizing a crash course in primers from an SME on them, issues arise from intersections of primer pocket dims, primer dims, seating method and depths, crimps, then all the stuff that happens at ignition and through the interior pressure cycle. The condition and location of the case, pocket, and primer (whole or remnant) tells the story. I.e. Pocket may be high side of spec or primer low side, machine seats it funny, crimp is wonky, round is overloaded or ok but in a tight chamber. Lots going on when you dive deep.