Cause of BCG lock up?

[Anatoly Lebed]

So yesterday at the range, I had to mortar clear my rifle. The round came out; the case looked ok. No marks on the primer. I loaded the cartridge again and the round went off. What could have caused this? The upper is relatively new, has probably close to 1,000 rounds through it. It’s the first malfunction I’ve had since the upper was assembled. This was the first session with a Colt MPC bolt I just picked up. Could it be that the bolt just needs to be broken in? Ammo used for most of the session was Guatamelan 5.56x45 M193, all shot with no problem. The round that gave me the problem was PPU Prvi Partisan 223 75 grain.

Upper specs: Noveske Gen 1 upper, Colt Socom 14.5 barrel, Noveske BCG, Colt bolt, Colt Copper color extractor.

[dpete]

How wet were you running it? A new bolt for an upper still has some breaking in to do and mating surfaces to mate. Could have been just an odd round too.

[m4luvr]

How wet were you running it? A new bolt for an upper still has some breaking in to do and mating surfaces to mate. Could have been just an odd round too.

yep- she needs to be wet or there’s no joy.

[gaijin]

Possibly debris in bolt.
And yeah, wet.

[titsonritz]

I would worry about it unless it is a reoccurring event.

[Anatoly Lebed]

How wet were you running it? A new bolt for an upper still has some breaking in to do and mating surfaces to mate. Could have been just an odd round too.

I’m hoping it was just a fluke. I only shot about 20 rounds of the PPU yesterday before the problem happened. Next outing I’m going to shoot more of the PPU to see if it was just a fluke or if the upper doesn’t like the PPU.

[Pappabear]

I would simulate the exact course of action while taking all the safety precautions to see if you can cause it again. Of course you can't get it to jam first but other than that, drop that bolt and see.

PB