bravofivethree

Follow-on fires

7 posts in this topic

Hello,Just put together an AR15 for my son. the bolt carrier was a bit tight but it seemed to work. Took it to the range to test fire it and in semi auto it fired 3 round bursts. Consistently. but the trigger wouldnt be reset after, you had to charge the next round to reset the trigger. When i put the bolt carrier from a different ar15 in it .. cycled perfect. single shots, no jams, worked fine.When i mic'd the carrier the bolt centerline was .025 low. Also the finish in the bore was really rough, not smooth like all my other carriers. So i have another carrier on the way from a different supplier.Anyone else seen this? How would a tight or off center bolt engagement cause the follow-on fires? I dont see a way to remill the carrier so thats a throw away. And with not resetting the trigger, it isnt really useful anyway. But I was just curious if anyone had some experience with a similar issue.Jeff

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This may sound like a dumb question...but..did you forget the spring under the sear?

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nope .. after the three shot group .. pulled the carrier and checked the fcg .. then reassembled and again the three round burst. pulled the carrier and put another carrier in it from another ar. fired ten rounds .. no problems, jams, misfires, or follow-on shots. Sent 10 more rounds downrange to confirm, no problems in the second group either.only thing that is different is the centerline of the bolt bore in the carrier, and the finish of the bore.i should get the new carrier in a day or two .. then its reassembly and back to the range.but with a correct carrier from another rifle, it sends rounds just fine.But that was a very good question. Thank you.

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Soundalike the trigger spring mightbe on backwards, cause the trigger pin to walk. That would be the first thing I would check.

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Well, after disassembly and mic'ing all the lower parts as well, it seemed the hammer was contacting the carrier on the backstroke, and the trigger notch wasnt cut correctly in the hammer. too shallow, wrong angle. Also, all the surfaces of all the trigger parts were really rough and had sharp edges.I corrected the hammer and the finish issues. put in a new carrier to fix the alignment of the bolt, and its smooth and reliable now.I'm thinking with the carrier contact and the minimal surface area of the trigger release, it could have bounced into unintended fires. I dont know for sure. i think the shallow cut on the hammer was the main culprit. The less than acceptable machine work on the rifle that was sent to me is a bit frustrating.Thank you for the input. it seems to be working well now.

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Soundalike the trigger spring mightbe on backwards, cause the trigger pin to walk. That would be the first thing I would check.
This would have been my guess

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Sounds like the same problem i had, except my BCG did fit.Fired just fine, cycled perfectly, chambered perfectly.but when it came to my next shoot, Nothing.Took it to a guy in the range office, looked inside the lower for about 5 seconds, asked who put it together, told him I did, and told me I forgot the disconnector sring. :smiley_green_with_envy:

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