henschman
Member
I have a M&P 10 that was experiencing some malfunctions associated with an under-gassed condition... failure to lock back on empty, and bolt-over FTE malfs. This is a common condition on M&Ps... for some reason it appears S&W thought it would be a good idea to design them so they only run reliably on close to max pressure loads. Not acceptable to me, as I shoot mostly surplus 7.62 NATO, and even the hunting hand loads I've been using are not anywhere near max pressure.
First I checked for gas block alignment. It was good to go, so I proceeded to drill out the gas port. I didn't do it too scientifically... I just found the smallest drill bit I had that wouldn't fit in the port, which was a 5/64", and drilled it out to that size. I put a cleaning rod down the barrel before drilling to keep the bit from nicking the other side of the bore when it came through, and really concentrated on keeping the bit straight. It was a really easy job... I did it in about 10 minutes this morning as an afterthought before joining a friend at the range. Anyway, the rifle now runs great on several different head stamps of 7.62x51 M80 ball, and always locks back on empty. The rifle's factory stock setup has also been replaced with an A2 receiver extension, AR10 rifle buffer and spring, and Magpul fixed rifle stock.
I'm really glad this thing runs now. I can continue with my planned mods. If any of you are having this kind of trouble with your M&P, don't lose heart -- drilling out the gas port is a pretty easy job.
First I checked for gas block alignment. It was good to go, so I proceeded to drill out the gas port. I didn't do it too scientifically... I just found the smallest drill bit I had that wouldn't fit in the port, which was a 5/64", and drilled it out to that size. I put a cleaning rod down the barrel before drilling to keep the bit from nicking the other side of the bore when it came through, and really concentrated on keeping the bit straight. It was a really easy job... I did it in about 10 minutes this morning as an afterthought before joining a friend at the range. Anyway, the rifle now runs great on several different head stamps of 7.62x51 M80 ball, and always locks back on empty. The rifle's factory stock setup has also been replaced with an A2 receiver extension, AR10 rifle buffer and spring, and Magpul fixed rifle stock.
I'm really glad this thing runs now. I can continue with my planned mods. If any of you are having this kind of trouble with your M&P, don't lose heart -- drilling out the gas port is a pretty easy job.
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