Maybe is just paid real good attention to the guy in the campaign hat at Ft. Knox, or maybe it comes from having a plethora of crappy magazines for my Mini-14 growing up, so seating magazines properly is ingrained into my psyche, but I never had a problem with the straight magazine well on the M-16/M-4 series of rifles.
Granted, I was issued some really, really crappy mags when I first got to my unit, but that was fixed with a run to Bass Pro and ten PMAGs.
Honestly, this is the first I've read of the straight magwell thing.
NRA Life Member
"Boy Scout Problem #18: Living with the fear that one day someone will find out you can't tie anything more complicated than a square knot."