I was able to talk to a different S&W customer service agent and I asked if there was any more details regarding the vague description of repaired the upper assembly that was listed of the last that was shipped back to me along with my M&P10. The lady on the phone said there was a note in the file saying the gas port was drilled out bigger to 1.85mm or 0.07283”. I’m not sure what the factory drilled gas port hole size was but this leads me to believe that the techs at S&W felt that my gun was under gassed which caused my issues. Though I am still a little confused that it worked fine with .308 ammo until the day the failing to feed started. Then it was having issues with both 7.62 and .308. I hope to get a chance to shoot it some this weekend and see how it works.