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Posted: 2/22/2013 6:54:31 PM EDT
| I have a DPMS 308 upper on a CMMG lower and 2 DPMS 10 round mags. Used it for approximately 4 months and 450 rounds with no problem. Now when the bolt pcks up a new round it will only chamber the round 3/4 of the way. This happens when you manually release the bolt or when it does fire and picks up a new round. It looks like the bolt doesn't quite seat over the lip of the round, so the round is crooked. The bolt, chamber, and bore have all been cleaned. Any thoughts? Thanks |
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You most likely need to radius your ejector face.
What has probably happened over the 450 rounds is that some brass shavings have entered the ejector channel. As the bolt picks up a cartridge, the cartridges is guided into alignment by the feed ramps and chamber, pushing the head up into the bolt face. What's supposed to happen is that as the case head seats into the bolt face, the plunger style ejector compresses fully as the bolt chambers the cartridge. In this case, it looks like a typical edgy ejector face that wins the battle against the chamfer on the case rim, causing the malfunction you see. Here's a radiused ejector: 
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