I did a lot of research before going with the M&P15 (specifically the "X"). There was--and remains--no doubt in my mind that it has ALL the important features for reliability--in terms of chrome lining in all the right places, M4 feed ramps, properly staked carrier key, etc.--and none of the esoteric stuff like magnetic particle inspected carrier (a holdover milspec requirement that just adds cost and is not needed). I've got a couple thousand rounds thru it: Federal XM193, Fiocchi, PMC, Federal AE223BK, even factory reloads from DMS and Tula steel case. No failures to feed, no failures to eject, one failure to fire on the AE223BK. My guess--it was a bad primer since the primer was dented the same depth as all other rounds shot that day, and the round fired after I re-chambered and tried again. With my 55 year old eyeballs, I was knocking down four inch groups of ten at 125 yds (max distance at my range). Maybe not sniper level performance, but more than enough to get any practical job done. I spent 29 years in the Marine Corps and shot the Colt A LOT. No complaints, but in my opinion it's got nothing on this weapon except a higher price tag. Like I said, I looked long and hard and went with the Smith and have been very, very pleased with my choice.
San Antonio, TX