17hmr2 vs 22lr: An interesting question for the "Caliber vs Caliber" file.
nds tight magwell: On the NDS-3 receiver, the magwells are frequently tight when you build them using a Romanian 'G' kit. This is probably because the NDS-3 is a copy of a Bulgarian receiver, and not a Romanian. I personally tend to dremel/roto-zip a little bit of the metal directly above the magazine release. Sometimes I end up shortening the mag latch itself. I should take some pictures of what I'm talking about, however...
identify bullet grain by looking at it: Grains are a weight measurement unit. You really can't weigh something by looking at it, nor are there any reliable/consistent visual indicators of how heavy a bullet is.