AR case separation

[superhondaz50]

I've had a tonne of ARs over the years, and my current one is having case separation issues. Barrel has less than 500rds on it (DTI, prob the issue). I was using an OE surplus Colt bolt with the new barrel. I just swapped a brand new Faxon MPI bolt with the same issue. Does it with new ammo or reloads. I need to find my headspace gauges, but am assuming the chamber is a few thou too long. More than likely just gonna buy a new Colt or BCM barrel. Anyone experience this?

[MajorSideburns]

That definitely sounds like a headspace issue. I would bet your chamber is out of spec and too long, as you already noted. Maybe the barrel extension lugs are too short. I would not continue shooting the rifle until you get this figured out.

[superhondaz50]

That definitely sounds like a headspace issue. I would bet your chamber is out of spec and too long, as you already noted. Maybe the barrel extension lugs are too short. I would not continue shooting the rifle until you get this figured out.

Ya, that's what I'm thinking. Barrels are cheap, just gotta shop around for a 14.5" M4 with FSB. Hopefully can find a Colt for good money.

[superhondaz50]

If anyone has a Colt M4 barrel (standard or socom) or 20" pencil they wanna sell, let me know.

[ar15robert]

Have had that happen a couple times with reloads and older brass. Usually a sign that that’s the last fire in that brass and the whole batch goes out. Had it happen in my old mini 14,my 16 inch ar and my 10.5 ar.

[mofo1111]

I would use a fired case out of that barrel and measure it. If it's over MAX headspace for 5.56 NATO, it's a bad chamber. You need to find your headspace gauges.

[superhondaz50]

I would use a fired case out of that barrel and measure it. If it's over MAX headspace for 5.56 NATO, it's a bad chamber. You need to find your headspace gauges.

I bought a new NATO Max gauge and the chamber is in spec. I just bumped the shoulder too far on old brass I think.