In my experience the only real difference is case life. Using commercial R-P & Win brass cases in my 7.62x51 chambered rifles has a distinctly shorter life before case separation. On the measure of 3-4 less firings before scrap. The other side is in my Custom Hart barreled Rem 700 I have 15 -16 loads on LC-83 match brass with no signs of separation yet.
A M16 is a fancy city girl, sexy as hell, but a bit moody. It's all good as long as you take her to the clubs and get what she asks. If you cross the? line, its over.
An AK is a naughty girl, all in latex and with a whip begging you to be naughty. The nastier you are the happier she is. Its clear that she wont dump you, you'll have to do that on your own.
The XCR is the perfect blend of both. Sexy as hell but willing to let you beat her and filthy her up and then beg for more.