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Posted: 6/30/2013 8:38:56 PM EDT
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Finished my build a couple days ago, and can't run a full 30 round mag without several FTFs. Barrel is 18" BHW with rifle length gas port, MI low pro gas block, M16 BCG, Brownell's rifle length buffer tube, spring, and buffer. I've tried several different types of ammo, mostly hot hand loads, but the same problem occurs every time. What I'm experiencing is the BCG stopping with the bolt touching the bolt catch.
So far, I've made sure that I've got plenty of lubrication, the gas port on the block and barrel line up and flows clean, the gas tube and gas key mate correctly, the bolt moves freely in the carrier, tried different mags, and that I have no obstructions or interference in bolt movement. The only thing that I can logically conclude to be left is the recoil spring not being heavy enough. Am I on the right path, or should I check for something else? |
| I feel pretty dumb right now. I failed to recognize that the feed ramps on the receiver and barrel extension didn't quite match up. The barrel extension ramps were overlapping the ramps in the receiver. I've always polished my feed ramps so that they match, but failed to do so this time. Spent a few minutes touching them up, cleaned it, lubed it, and now it runs just fine. Saved myself $18 for a spring, plus shipping. |
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