I'm in the process of test firing My ar after a kaboom (see my thread with pics in the troubleshooting section), I've checked my original bolt, the one that come from factory and is perfect, no ding or scratches anywhere, I've installed a new extractor, and a new bolt carrier, made by colt (the ar is an Olyarms), I've performed all the controls in the troubleshooting section, and everything went smooth and nice.
In the process of examining the barrele extension, I've noted that the lug at 2'o clock, the one corrispondent to the extractor claw, is slightly (maybe 0,8mm) dinged.
The others are perfect, I've checked with strong light and 4x jeweler goggles. Also the chamber and the distance between barrel and barrel extension is correct.
The lug was dinged because the extractor was forces outside and bent from a brass failure that lead to a KB, shredding the bottom of the bolt carrier.
Now, my question is, it is safe my ar even with this small ding on the lug? I've checked headspace, extraction and even percussion of the firing pin (putting a primed empty brass in chamber and firing it) and everything went perfect.
Right now I have only to test fire the thing, and I don't want to risk another KB.
I wish the ding in the lug didn't compromise safety, 'cause I'm from Italy, and..just obtaining a new BC was en epic struggle (see my posts..), having a new barrel extension installed by a gunsmith would be something highly remote here...
Thanks for info, guys..