Have a Leupold VX-Freedom 3-9x40 that I'd like to mount to a 16" 5.56 AR. New to the scopes and rings part as I'm used to plain Magpul BUIS. What are the main differences between a set of rings or one piece? Is getting one of the forward cantilevers at all helpful? Are there any specific brands to look at or avoid? Also, in eyeballing it sitting on top, to would seem the charging handle may get a bit hidden, so do most upgrade to a larger one (Radian, Geissele, Primary Arms, BCM, etc.)?