mostly they use 5.45x39 in their ak's, but they have 7.62x39 somewhere.This is a absolute nightmare. There is nothing wrong with the 5.56 as a combat cartridge as you can see in the Ukraine. I carried the M4 as a contractor in Iraq and always carried 400 rounds of ammo and that is something I could not do with this abortion. If I was Grizzly hunting sure but for people massive over kill and too heavy.
i never used a M4, it was M16A1 or A2. the 5.56 is a good 300 meters/yards and under combat cartridge. but once you over 325 - 350 meters/yards, it has a problem or problemS. the 7.62x39 and the 5.34x39 have the same problems. i felt that i was under gunned with 5.56, probably because i was a hunter.
back in my day.....they didn't have the cartridges that they have now....6.5 Grendel or 6.8 SPC or.....whatever. (wildcats are not included) we had the 5.56x45 and the 7.62s51 and 50BMG. in my mind, the 5.56 and 62gr M855 was a groundhog gun. fun to shoot but it just wasn't fer me. the 7.62x51 however, was "the man's cartridge". but it was only available in the M60 machine gun and it weighed about 20 lbs. "the Pig" was a good name for it, heavy, loud and has a voracious appetite for bullets. i luved to shoot it, but hated to carry it.
NATO has finally got its act together (finally has 5.56x45 for all nations) and then we do this poop, 277 Fury and oh, by the way, the old rifles? get rid of them. buy an ar 10 action and go from there. you've got to kidding me? do a 2 piece body case if you HAVE to and do a new barrel for 6.5 Grendel or other 5.56 cartridge length.
yes, i feel the 5.56 is under gunned at above 300 meters/yards. but there is a range of cartridges and length (5.56) to go after.