Oddest AR Jam I've ever seen

[Weg]

Anyone ever seen anything like this?

I was shooting my AR last weekend with 55 grain reloads. I had gone through 2 - 30 round mags. when I got a jam. The gun was VERY dirty as I had a suppressor on it, and had not cleaned it in 200 rounds of suppressed shooting prior to that. The bolt came exactly half way to the rear with the expended case still held by the extractor and locked solid. It locked just short of where the case would clear the port. I tried the forward assist but the bolt/carrier would not budge. I then went to my garage and inserted a cleaning rod down the barrel, and into the spent case. I began tapping with alot of force, which moved it rearward but did not free it. I stopped at some point as I realized I was beating the bolt back and not freeing anything. I then used a brass drift and began to tap/beat it forward by leveraging it against one locking lug on the bolt. After 3 or 4 taps the bolt snapped into battery. I stripped the gun down and have found nothing. No metal, no loose gas key, no broken forward assist, nothing. I then ran 40 rounds through it without a hiccup. Anyone ever seen anything like that? I hate it that I can't find anything that could have caused a jam that bad.

[tlt]

Similar weirdness with Russian steel case cheap ammo. I've since switched to a piston system, and stopped using anything you'd consider budget ammo. If sounds similar to a scenario where the firing pin retaining pin was not installed right and / or could break or come loose and jamb things up. I'd tear it down and look carefully for anywhere it might have rubbed.... Odd one for sure. The make a case extractor for this caliber for a reason though I suppose it can happen.

[The Annoyed Man]

Is it possible that the cam pin channel was dry, and the cam pin seized in its channel, locking the bolt in mid-stroke?

[Weg]

Is it possible that the cam pin channel was dry, and the cam pin seized in its channel, locking the bolt in mid-stroke?

Never thought of that one, the action was pretty dry and very gritty, what baffles me the most is it was so frozen that hitting the forward assist would not even break it loose. I was looking at the case again after posting this, and noticed it is missing a small chunk of brass at the tip of the neck on one side. I don't think I broke that off with the cleaning rod as it was in the case when I was tapping on it. I'm now beginning to wonder if that piece some how ended up in the action? But then again, i'm thinking that is unlikely as it would have had to made it from where it came off, all the way back into the action and jam it before it even completed it's cycle rearward.

[TheDude]

You notice if any cases had a blown primer? Those things can get down in your gun and cause issues and then slip out without you ever finding them. I have heard of them getting into the trigger assembly and causing all types of issues. Maybe one got stuck in the cam pin keeping it from moving. It might not even have been from the case that you had just fired.

[MechAg94]

One time years ago, I was shooting cheap gun show ammo that came in bags. I thought I would just shoot it to break in the rifle. I had several primers that fell out, but most caused no issues. Once the bolt jammed up. I field stripped it. There was a small sliver of brass that got behind the bolt and stuck things up. It worked fine after reassembling. I am not certain if my problem was the same as yours. That was my first AR and I knew little about them. I assumed the sliver of brass came off one of the blown primers.

During that same session, I tried to eject an unfired round. The bullet stayed in the chamber and the brass casing was ejected. Unburned powder was scattered all over the chamber and bolt carrier making a mess. I wasn't happy with that ammo.

[Weg]

Did not think of it possibly being caused by a previously fired round. Once the rain stops i'll go out and look at the brass, I never got around to picking it up, so I should be able to find all of them and see if any have a blown primer.