Back in December, I picked up a BCM extractor spring upgrade. The upgrade came with the new insert, coil, and o-ring. I’ve used it with the O-ring, but I notice that the end of the .223 and 5.56 casings (after the round’s been fired) is getting scraped/gouged. This is a Stag upper with a standard stag/CMT bolt carrier. Before I got the extractor spring upgrade, only the 5.56 casings were getting scraped (this is with the blue insert and old spring). I heard somewhere that the O-ring might play a role in this, but I’m not really sure. If the O-ring is part of the cause, should I retain the O-ring, or should I remove it? If memory serves me right, I think using a H-buffer might help as well, but since I also shoot lighter loads, I want to keep my current carbine buffer. This probably isn’t too big of an issue, but I want to save the casings because I have friends that reload.
Below are pictures of Sellier and Bellot .223 FMJ (55gr) and Winchester 5.56 FMJ (55gr).
It only said that the coil was so strong that the o-ring wasn’t probably wasn’t even needed, but was included anyway.
Before the spring upgrade with the old spring and blue insert, the Winchester 5.56 casings were getting gouged, but the .223 ones were not as much.
Does anyone know if removing the O-ring will stop the scraping/gouging of the casings?
The upper mark in your pictures is from the ejector. It is more pronounced w/ the 5.56 because of the higher pressures (note the flattened 5.56 primer). Is your extractor “smooth” I use this term loosely, since what I really mean is there a burr on your extractor. If your not having extraction problems, just run with the spring.
You guys think he may be a bit over gassed?
I dont get marks like that in any of mine so far. I would try an h buffer or heavier and see if you get marks like that. If you dont then try either one with the lightest load ammo you have to see if it cycles properly.
The markings on the caseheads in the original post have nothing to do with o-rings. The brass of the casehead is flowing into the ejector and extractor cuts of the bolt-face causing those marks.
