Weird AR fail.

I would bet your receiver extension tube needs to be threaded in further. That is a weird one though....

At least it was easy to diagnose. My wierd one was that I would shoot a round and the gun would cycle, and then for the next shot I got a click and when I would go to put safety on it would fire. That took a while to figure out. Lower out of spec... my 80% so I couldn’t complain but it was hard to figure out.

As I recall, the buffer tube is supposed to retain the buffer tube retaining pin, with just enough clearance to let it be pushed down.

taliv said:

What’s up with the face on that hammer?

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Was wondering the same thing. At first I thought that was the issue, until I saw the spring all bound up down there. Looks like it’s been burned and hit really hard by the firing pin or something. Does back pressure from suppressors cause that kind of marking?

Trey Veston said:

I had removed the brace to install a sling attachment plate...

Anyone else had weird failures like that?

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If the new receiver end plate is too thick it can prevent the buffer tube from screwing in far enough to retain the pin and spring. And if the buffer tube is already a hair short or the retainer hole is just a bit forward you can quickly run into tolerance stacking issues.

I like the POF anti tilt buffer tube. I never heard of carrier tilt and don't even know if it's a benefit to a non piston AR, but what I do like about it is it's 7075 and has a lil recess cut into the threaded end of the tube to shroud the buffer spring retainer so there is no possible chance your buffer tube can rotate and cause this or other malf's, the retainer button literally has nowhere to go and the tube has no way to rotate out of place.

I'm pretty sure it allows your buffer tube to have a few more threads engaged into your upper for added rigidity.

My brother had a strange failure one day when we were shooting with his police issue Bushmaster. Loaded a round. Bang. And then a FTF (feed). Close, but no cigar. Hits the forward assist. Nada. Dumped the mag and tried to eject the cartridge, it’s stuck. Boot trick. Worked. Cycle it, dry fire, cycle, dry fire. Good to go. Load in another mag, drop the bolt release, failure to fully chamber. Drop mag, try to cycle bolt, it’s stuck again. Boot trick worked. At this point we decided to completely field strip it. And that’s when we discovered a complete 223 neck in the chamber. Factory Hornady ammo. Remove the embedded neck, and we were back in business.

I have also seen a primer fall out and work it’s way under the trigger becoming a “safety” that required disassembly of the trigger group to fix.

7mmsavage said:

Was wondering the same thing. At first I thought that was the issue, until I saw the spring all bound up down there. Looks like it’s been burned and hit really hard by the firing pin or something. Does back pressure from suppressors cause that kind of marking?

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Gas is blowing back past the firing pin. The firing pin hole may be oversized, or you may have defective gas rings.

I made that whoopsie with not threading the buffer tube far enough in on my AR pistol. Fixed the retaining pin with a spring from a ball point pen. I had bad ammo that was making me neurotic with cycling issues.

Funny this thread should come up. I had what i thought was an issue with my 300 blacout loads not properly cycling. I cleabed the gun well inckuding the BCG. So i loaded up a set of loads that are subsonic and hit the range. Normally i shoot heavy 225-230gr bullets slightly on the supersonic side.

I get to the range ( no target needed after all its just a cycle test ) with 2x30 rnd mags. But somethibg was different .

With the lighter loads i notice it sometimes was not extracting. Odd. Extractor looked good. Held on to empty brass well so i threw it back in and finished the loads off and headed home.

So when i got home i figured i would take the extracror off, clean it and insect it as well as the ehector.

2 light taps on the extractor pin and half of it fell out! Extractor remained with the ither half of the pin holding it in.

I guess you could say this is not uncommon as parts do break on AR-15's. But this pin had me flustered.

Needless to say i ordered a few of them so i would have at least one spare between the 2 AR-15's i have.

jmorris said:

I have also seen a primer fall out and work it’s way under the trigger becoming a “safety” that required disassembly of the trigger group to fix.

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I’ve had the same as the result of poorly swaged primer pockets on surplus brass.

That certainly is weird. I have seen lots of AR malfunctions but that is a first for me. Are you using any non standard parts like castle nut extension, exotic endplate, or something like that?