Buddy of mine has the M&P15. To my knowledge, never had an issue, and he shoots a lot more than I do. I had 2 StrikeFires, not the II. Large field of view (doesn't matter when both eyes are open, but provides a more forgiving eyebox to see the dot), bright dot, decent battery life. They are heavy for a dot, though. One thing I did like, was when the battery was almost dead, it wouldn't turn OFF. It stayed red, couldn't switch off or to green. I liked that, even if it didn't make sense. Had a Sig Romeo5 after that which was lighter and better battery life, but smaller FOV and cheaper materials (I stripped a screw hole mounting it, and had to drill out the mounting bolt when I removed it). For a basic red dot, Vortex is good, but heavy.