Smith & Wesson M&P 15-22 internal parts overview

I discovered a few things about the M&P 15-22 when I took it apart for the pre-cleaning before it's first range trip:
1- the rails on the bolt assembly are roughly manufactured.
2- a standard AR-15 hammer can be used as well as trigger
3- the bolt release is proprietary and not replaceable with a standard AR-15 bolt release.
4- for reasons unknown I had to move the NcStar reflex sight back about an inch to get the reticle to center.
Overall it seems to be well built and should work well.
....range report coming soon!