So I got some 9mm 147 gr. ammunition. The guy who sold me my XD subcompact recommended it to me in place of Glaser safety ammo. Well, I get home and start looking around the internet a bit, and I hear some cautionary things, ranging from optimum performance is had with less than 124 gr. all the way to never use 147 gr. At any rate, I don't know what the fuck grain is or what type of grain ammo to buy.