AR barrel/chamber chewing bullets

[TradLife406]

A few years ago I built a 12.5 using a Rainier barrel.
The gun is left hot and safety on.

I pulled it off the wall to mess with the suppressor and cleared it. I've had some issues with this chamber and rounds sticking. It ejected just fine but the bullet is chewed up!

Looks like this pipe is going to the scrap heap then I'll order a criterion or something.

 

[Thegman]

Not so fast...

Those are just gouges from your barrel extension lug cuts. Your next barrel will more than likely do the same.

It's very easy to address. Search the UL-UL thread for information I posted on fixing that (very common) AR-15 issue.

Also an article in G&A AR-15 about 3 issues back with instructions and pictures.

This should give the general idea.





Also, you will get some minor bullet gouges upon extracting the cartridge as the ejector pushes the cartridge to the right, up against the 3-O'Clock lug cut. To isolate those gouges, hold the cartridge in line with the chamber as you extract it, until it's past the lug cuts.

 

[RockAndSage]

Sometimes a barrel extension's lugs can have sharp edges and cause that kind of bullet damage. A cratex bit on a grinder can polish up the ones near the ramps fairly quickly.

If you're getting resistance in extraction though...one diagnostic is to see if it does that with empty casings too, in manually extracting them. If yes, it can be a sign of a rough chamber.

Did you use all three headspace gauges on it when you built it?