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Posted: 12/10/2010 10:22:21 PM EDT
This..
It's out of an LMT MRP and the rifle quit working while out shooting. Pulled the upper off and noticed where the piston rod hits the carrier was all mushroomed and cracked. It had Hornady tap 75gn ammo it it when it happened and has had m-855 and everything else fired through it and it probably has 2000 rounds or so down range. Only other problem it's had was it devoloped a nasty burr on the left feed ramp and was causing FTF's like crazy. Filed the burr down and it was fine... |
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Looks like an op-rod is out of alignment. Something is causing that op-rod to hit the edge (sort of) as it is traveling into the pocket. So is the rod wobbling in the upper, which leads to, is there a bushing missing, or is the op-rod port out of tolerance, is the op-rod out of tolerance? Just giving you ideas to trace. |
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Quoted:
Looks like an op-rod is out of alignment. Something is causing that op-rod to hit the edge (sort of) as it is traveling into the pocket. So is the rod wobbling in the upper, which leads to, is there a bushing missing, or is the op-rod port out of tolerance, is the op-rod out of tolerance? Just giving you ideas to trace. The op-rod doesn't seem to be wobbling but I'll look into it a bit more. As far as the missing bushing and out of spec op-rod, I have no idea. Is there a diagram of the op-rod so I can see where the bushing goes and if it's still there? And what do I need to measure to determine if the rod itself is out of spec? The tip of the op-rod itself is fine also... |
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is there excessive end play in the op rod with the bolt carrier forward?
did lmt give a reason for why this might happen? I would think the bushing is similar to the one in my osprey kit in that it just presses into the upper where the op rod comes through ( from the inside) |
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Sorry don't run that system. I'm approaching this from a Quality Engineer perspective to determine the problem. If there is no wobble I would look some sort of misalignment of the rod, maybe an out of spec carrier. Quoted: Quoted: Looks like an op-rod is out of alignment. Something is causing that op-rod to hit the edge (sort of) as it is traveling into the pocket. So is the rod wobbling in the upper, which leads to, is there a bushing missing, or is the op-rod port out of tolerance, is the op-rod out of tolerance? Just giving you ideas to trace. The op-rod doesn't seem to be wobbling but I'll look into it a bit more. As far as the missing bushing and out of spec op-rod, I have no idea. Is there a diagram of the op-rod so I can see where the bushing goes and if it's still there? And what do I need to measure to determine if the rod itself is out of spec? The tip of the op-rod itself is fine also... |
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Quoted:
This.. http://i708.photobucket.com/albums/ww90/pathell/1292048960-1.jpg http://i708.photobucket.com/albums/ww90/pathell/1292048960.jpg http://i708.photobucket.com/albums/ww90/pathell/1292048958-1.jpg It's out of an LMT MRP and the rifle quit working while out shooting. Pulled the upper off and noticed where the piston rod hits the carrier was all mushroomed and cracked. It had Hornady tap 75gn ammo it it when it happened and has had m-855 and everything else fired through it and it probably has 2000 rounds or so down range. Only other problem it's had was it devoloped a nasty burr on the left feed ramp and was causing FTF's like crazy. Filed the burr down and it was fine... Have there been any updates on the issue or fix? |
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