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Posted: 4/28/2006 12:18:35 PM EDT
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Hello AR dudes. So today I got to testfire my first AR, a Colt SP-1 upper on a Dalphon lower, with an anonymous BCG. I was firing 5 round strings, and got a FTF about 10% of the time, with the bolt denting the brass, wedging the case about 30% out of the magazine. Details: - Winchester Q3131 - Okay Ind. 30 round mags, new, and a new Brownells 20 round mag. - Dalphon lower with Armalite LPK - Colt SP-1 upper, big takedown pin hole, I'm using a bronze bearing bushing as a pin adapter. Here's what's odd: it takes a LOT of effort to push in or push out the rear takedown pin when the upper is in place. I can't budge it out of position by pushing on it with a bullet tip, I need to use a brass punch and a hammer to move it. There's also a visiable air gap between the upper and lower, maybe 2 sheets of paper thick. My thinking is that I've got severe tolerence stacking working against me. Should I try one of CDNN's universal front pins instead of the bushing? Or should I ditch the Colt upper and find another one that fits better? Or am I barking up the wrong tree? (as usual) Thanks! |
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If I understand correctly, you are using a concentric bushung to take up the size difference between the hole/pin diameter in the pivot pin area. To the best of my knowledge the adapter pins have a eccentric set up....the centers don't lineup. It is a sort of offset pin. I think that is your problem...for sure. Yes, you will need the pin from the link..... |
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