Bolt Carrier Issue

[ETX-Deerslayer]

I’m not sure what to title this thread and I’m sure I won’t be able to explain it well enough, but I’ll give it a shot.

My son was shooting his AR suppressed today. First time with a suppressor on this AR. He shot 3 mags and the failure happened with round #90 of the day….. yes final round in the last mag. Last 15 or so rounds were in fairly quick succession.

This is a BCM 14.5 complete upper that he has had two years. Probably have ran 3,000-4,000 rounds through this set up. Built on an eagle arms lower. He was running a mini 2 surefire suppressor and factory 55gr ball ammo. Winchester.

When he fired that last round the pressure blew out the bottom of his magazine see pic below. Bolt carrier is not movable at all. It looks like the jaws of the extractor / boltface has cracked the lugs where it meets the barrel. I tried to take a pic but can’t really see it. Anyway….. we are not sure what caused this ‘over pressure’ and are curious if it was an ammo issue, suppressor pressure issue or what could have caused this? (All rounds prior to this last one were fine…. No barrel obstruction etc)


I’m sure this is probably not enough info and I have not explained it very well.

Regardless…. Upper is toast and we will figure out a plan b.






He took some powder burns to the arm but is otherwise fine.

Thoughts?


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[doppelganger]

I do normally go up to an H2 buffer spring with a suppressor. Something to slow down the reciprocating of the BCG. Not sure the increased force of the bcg reciprocating did it. Does seem like it wasn’t fully locked in when it fired. I’ve never had such an issue, sorry I’m not any help specifically.


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[doppelganger]

What suppressor?


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[ETX-Deerslayer]

What suppressor?


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Surefire mini 2


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[BlessedVeteran0305]

It sounds like too much pressure built up when shooting those last few rounds at a higher rate along with the pressure possibly forcing the bolt back. As far as the bolt being stuck it could be that the bolt slid fwd too fast along with the heat of the blow back and maybe lodging it in the chamber. The upper sounds like it's toast especially if you can't pull it back. I would try to knock it back with a cleaning rod down the barrel.

[ETX-Deerslayer]

It sounds like too much pressure built up when shooting those last few rounds at a higher rate along with the pressure possibly forcing the bolt back. As far as the bolt being stuck it could be that the bolt slid fwd too fast along with the heat of the blow back and maybe lodging it in the chamber. The upper sounds like it's toast especially if you can't pull it back. I would try to knock it back with a cleaning rod down the barrel.

We have hammered on it with all we got. Lol.

So, what would be the solution to the above issue? If this is what happened?

Thanks


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[doppelganger]

Put it on a wooden plaque and hang it on the wall


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[BlessedVeteran0305]

We have hammered on it with all we got. Lol.

So, what would be the solution to the above issue? If this is what happened?

Thanks


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I would say it's toast. Sounds like the heat may have "welded" the bolt shut. Are you able to take the lower off and post a picture from the bottom?

[ETX-Deerslayer]

Yep we know the upper is trashed. Just trying to avoid the same sort of failure in the future. We got the lower off. Pics below. Hard to really see……





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[Mike D]

I’m going to bet an overpressure round. Winchester white box was notorious for that in years past.


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[BlessedVeteran0305]

Judging by the burn marks on the bottom of the chamber, there was definitely too much pressure. I would try using a different spring known for use with suppressors next time as mentioned above.

[Clay C]

That was not caused by increased pressure from a suppressor or having too weak of a buffer spring. Either an overcharged round, or it fired out of battery. Possible to get a lot number on the ammo?

Did it eject the brass? You said y’all are ramming a cleaning rod down he barrel trying to get the bcg to move and no dice. Are you sure you’re hitting the bolt? Your Son doesn’t happen to own a .300 blackout, does he?

Regardless, that could have been really bad. Glad he wasn’t hurt. Great reminder to always wear eye protection

[BTLowry]

That was not caused by increased pressure from a suppressor or having too weak of a buffer spring. Either an overcharged round, or it fired out of battery. Possible to get a lot number on the ammo?

Did it eject the brass? You said y’all are ramming a cleaning rod down he barrel trying to get the bcg to move and no dice. Are you sure you’re hitting the bolt? Your Son doesn’t happen to own a .300 blackout, does he?

Regardless, that could have been really bad. Glad he wasn’t hurt. Great reminder to always wear eye protection

This was my first thought as well
Will be checking back to see if cause is ever determined

[ETX-Deerslayer]

Does not own a .300 blackout. Do not think it ejected the brass.


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[Clay C]

Does not own a .300 blackout. Do not think it ejected the brass.


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See if he has the lot number for the ammo. Get it and do some googling to see if anyone else has posted about having an issue with it. This sounds like an ammunition issue. Do you know if it is Lake City XM193, or .223?