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Posted: 12/18/2010 10:47:59 AM EDT
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I bought a bunch of Black Hills 68 gr. Match ammo for my Spikes 1 in 7 and it runs flawlessly using the Spikes heavy buffer. At my last range session I tried it in my Stag 1 in 9 with an H buffer. Using the same P mags, the second round in each mag had bullet set-back and, luckily, would jam. The bullet was pushed back into the case so the point was almost even with the case mouth. Subsequent rounds in the mag were fine. If it has any bearing on the issue, The Stag with a Wolff extra power extractor spring ejected fired cases at 2 oclock and the Spikes with factory spring ejected them at 4 oclock. Any ideas, I'm stumped.
Thanks for all the suggestions. I ordered a Spikes BCG and went to the range with it installed this morning. It ran flawlessly with 68, 62 and 55 gr. rounds. Called Stag when I got home and they emailed me a prepaid shipping label and the OEM BCG will be on it's way to them in the morning. Pleasant, no hassle, customer service. |
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Go back and retest the trouble rifle with a single round in the mag to confirm that the rifle is full stroking, hence bolt locking back on the catch after that single loaded/fired shot. The 68 gr ammo uses slower burning powder to get it up the speed, and that powder has a slower burn which puts the burn spike closer to the barrel gas port, increasing the amount of gas the action sees to self cycle.
If the rifle is full stoking, then it comes down to the mag recovering in time for a clean round strip, and even the angle of attack out of the mag for the round to enter the freed lips cleanly, and not be low feed into the the upper reciever below the feed ramps. And so you know, the bullet has a longer ogive, and reason that the M-4 rifles had extended feed ramps (to prevent the round nose from striking the upper receiver below the feed ramps). |
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Quoted:
Go back and retest the trouble rifle with a single round in the mag to confirm that the rifle is full stroking, hence bolt locking back on the catch after that single loaded/fired shot. The 68 gr ammo uses slower burning powder to get it up the speed, and that powder has a slower burn which puts the burn spike closer to the barrel gas port, increasing the amount of gas the action sees to self cycle. If the rifle is full stoking, then it comes down to the mag recovering in time for a clean round strip, and even the angle of attack out of the mag for the round to enter the freed lips cleanly, and not be low feed into the the upper reciever below the feed ramps. And so you know, the bullet has a longer ogive, and reason that the M-4 rifles had extended feed ramps (to prevent the round nose from striking the upper receiver below the feed ramps). I didn't think of the slower burning powder being the issue. That may just be it. I failed to mention that the Spikes is a mid-length so that may be why they function fine in it. Both have M-4 feed ramps though. Thanks |
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Quoted:
Only thing I can think of right off hand is maybe the followers in the P-mags are hanging up and they are not pushing that second round high enough and it's getting slammed into the receiver and jamming. Thanks for the input. I think the rounds are getting slammed into the receiver but the same mags worked fine in the Spikes. I think the slower burning powder may be the issue since the Stag runs flawlessly with 55 gr. rounds and have never had a malfunction with it until I tried 68 gr. |
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