Fired case from out of battery AR-15?

[Shrinkmd]

I haven’t cleaned the buffer or spring in a while, it was dirty, and I wiped it off. It feels like the end of the spring was stuck around the rim of the buffer, is that how it typically is? It is an H1 buffer.

Would a work buffer spring lead to these issues?

 

[Nature Boy]

I hadn't noticed before, I will have to keep an eye on that.

Pick up one of these primer pocket gauges and check your brass when primers start to feel a bit too easy to seat. It will save you a ruined bolt face.

 

[Lo-Profile]

Looks like the primer wasn't seated deep enough and the bolt face hit it hard enough causing it to fire, hence the small round mark and seemingly light primer strike

 

[243winxb]

The round fired while the action was locked. The powder did not start burning correctly. Action started to open. A 2nd pressure spike was enough to expand the case mouth.
The primer in the mean time was not against the bolt face. Primer backed out, leaking gas.
When bolt unlocked, firing pin retracted, no longer touching primer. Primer flow.

Was a spray used to lube the brass at sizing, contaminating powder near the primer? Water or tumbling media in the case.

When the primer fired, the bullet may have moved to soon. Check bullet hold, neck tension. Acted like a pluged bore, caused secondary pressure spike.

Something changed the burn rate of the powder, causing a secondary pressure spike.

 

[243winxb]

I totally remembered my rifle doubling The trigger is a LaRue double stage which has probably 2k on it, I haven't messed with any springs or done anything to it, so it's possible it's acting up?

Caused by an after market trigger problem. To light? Hammer slips off sear after being delayed a tenth of a second. Action locked at firing.

 

[243winxb]

swager

Primer pocket enlarged or out of round when swaging. Gas leak.

 

[jmorris]

I watched a slo-mo on the M14 action... and I was surprised, you could clearly see the bolt bounce.

You should watch high speed video of an engine valvetrain at high RPM.

 

[Random 8]

Have you had any issues with your trigger not resetting? I recently did a trigger upgrade on a cheap DPMS carbine. On my install, the disconnector spring somehow got torqued out of position and mashed, giving me an erratic trigger reset. While test firing for function, I got a couple of doubles and one fired case in a similar condition to yours, but not as severe, I still have a little neck left, and without the backed primer. Not sure of the exact mechanics at play here, but I could imagine a faulty, damaged or obstructed disconnector spring or disconnector impedance could cause this issue. Replacing the OEM DC spring (correctly) solved my issue.

I've also seen this in a SR match, another shooter with too hot loads had a primer anvil from a blown primer work down into the guts of the trigger assembly.

 

[Shrinkmd]

Lots of good ideas and thoughts. Overall my process has been the same for a few years. Same dies, bushing, brass, 1050 settings, really the only different variables are the Win 41 primers instead of the CCI (or old Wolf 556) and everything is an another year or two older.

I tumble all the lube off after sizing. I’ve got the Redding 22 cal carbide sizing ball setting the tension. Gracey trimmer. Same bullets…

I will check the trigger assembly more carefully and make sure nothing is caught in there.

 

[Charlie98]

FWIW, my gen-u-wine Colt H-Bar doubles once in a while. I put it down to the absolutely horrible trigger it came with (...as a Match rifle?) because I don't have those problems with any other AR I have. It's a Big Pin lower, so I have to save my pennies for an aftermarket drop-in.

I've had issues with bad primers piercing around the outside edge... this with Winchester LPP's..

...in the photo, you can see the flame cuts on the recoil shield of my S&W 57. It did the same thing to the bolt of my Marlin 1894, too. I don't consider it a safety issue, per se, but it's not something you want to continue.




Judging from the photos... the bolt looks ok. The more I look at it, the more I think it was a ignition/burn issue and/or/coupled with a bouncing or opening bolt.

 

[Gone Hiking]

I'm guessing the primer was high and was detonated by the bolt face the instant the bolt lugs came into contact (met resistance) with the locking lugs, but before the bolt rotated into battery. So yes, an out of battery firing.

 

[Shrinkmd]

The shell plate was loose on the 1050. I tore it all down and cleaned everything, inside and out. All primers are now seating slightly below flush, and my rifle back to functioning flawlessly. Lesson learned.