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Posted: 2/10/2012 11:32:36 AM EDT
| I have a flat top upper reciever (brand unknown) without m4 cuts, with a dpms 24in heavy bull barrel with m4 cuts, when trying to pull the charging hammer it takes a team of elephants to pull back.if you try to ease the bolt forward it gets stuck right as the bolt enters the lugs. Now the same bolt, carrier and all in an A2 upper reciever with the same barrel, has no problems at all. I used this flat top on a carbine build and had no problems, any ideas? |
| Compare the center of the feed ramps to the front take down lug to make sure that the barrel is not slip/twist in the upper barrel socket when the barrel nut was tightened, and then with the carrier alone (bolt removed), dry fit it into the upper receiver to make sure that the gas tube is correctly aligned to the carrier key. |
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Quoted: Compare the center of the feed ramps to the front take down lug to make sure that the barrel is not slip/twist in the upper barrel socket when the barrel nut was tightened, and then with the carrier alone (bolt removed), dry fit it into the upper receiver to make sure that the gas tube is correctly aligned to the carrier key. This^ On one of my early builds this exact same thing happened to me, come to find out the barrel extension had rotated ever so slightly when I torqued the barrel nut, it was barely visible to the eye, which was binding the lugs of the bolt on the lugs of the extension going in and coming back out. Once I loosened the barrel nut and realigned the extension all was good again. |
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