Hoping to get my kids into high power shooting this coming spring I put together a nice match AR-15, 24 inch Walter barrel 1-8 twist, nice match trigger etc. I am considering getting a scope for it and was looking at the Nikon M223 4-12 and there are two models. One with BDC in scope and the other with the compensator built into the top adjustment nob. I am wodnering if anyone had any opinions on them and which they would buy and further if 4-12 is powerful enough out to 500 or 600 meters. I was also looking at a quick release for the scope since the kids will primarily be using peep sights. Any thoughts on the mount?