Received my lower from BCM today, and when I went to insstall the BCG, I noticed the package has a very small black rubber o-ring gasket. Is this critical, or is it a spare? ...and where does it go?
I really need your help, because until I get it figured out I can't send y'all any pictures...so its in your best interest to help!
Oksy it appears to have something to do with the extractor. Does it go under the spring inside the extractor or over the spring and pin between the extractor and the bolt?
Rubber O Ring Extractor Enhancer as used in the M4, SPR and CQBR Rifles. Enhances extractor tension x4 for reliable operation in short barreled and full auto weapons. Installs around existing extractor spring under extractor.
You can buy a package of o-rings at a hardware store. The right size is the one that goes easily, but snugly, over the extractor spring.
They seem to be very durable. Obviously, if you do lots of shooting, the heat is going to break down the rubber sooner than later. Simply replace the rings on a regular schedule, like whenever you give the bolt a good cleaning. Only takes a minute and the rings are not expensive.
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