Thats probably what a M240 would be good for, the 7.62x51 has twice as much powder than the 5.56 or 7.62x39 therefor louder BOOM.I own both. I have never been downrange of either rifle while shooting them. Having never been in combat, I have no idea which has a louder sonic crack.
I was reading a document the other day regarding the theoretical advantages and disadvantages of various aspects of a possible replacement military cartridge. It suggested (probably from input by people who know) that larger caliber bullets, which must displace more air, have a substantially louder sonic crack, and that larger calibers were therefore able to provide more psychologically effective suppressing fire.
I guess maybe the AK sounds flat compared to the harder sound of the M4?One problem is that it depends on which compensater your using. An M-4 with a Lavang comp will direct more sound down range thanone with a standard A2 comp will.
With a 16 inch barrel it sounds like the AK is louder than the M-4, but as stated before, the 5.56 x 45 round has a sharper crack to it than the 7.62 x 39. The M-4 has a barrel 14 inches long and it seems louder. I have never actually measured the sound, I shoot with some guys who have both, and while I don't sit down range and listen to them shoot at me, I do hear them fire from the side.