It's clear that you've never been on the receiving end of 7,62x39mm M43 AK rounds from an RPK or RPD machinegun from 500 meters, trying to wish an extra 200 meters range from your M16A1...which was what the Salvadorians were using last time I was down that way. The Guatemalans, using Israeli Galils with 1:12 twist barrels and 55-grain M193 ammo, had it even worse.
The AK round was of course first used in the Siminov CKC/SKS carbine, with a 20.5"/520mm length barrel; the performance was a bit degraded with the adoption of the 16-inch barrelled AK47, but the squad's 24-inch barrelled RPK squad automatic weapons make up the difference just fine.
Meanwhile, we increased the weight of the M16 to almost that of the Garand and adopted the heavier bullet 5,56mm M855 ammunition to increase that rifle's range, only to then replace most of those heavy old things with cutdown M4 carbines with 16 inch barrels...while the Russians went to the AK74 with a 5,45mm cartridge designed to be used from that 16-inch barrel in the first place...and in those long-barrelled SAWs, still found in every squad, as well.
500-meter work, under harsh enviornmental conditions? Give me an RPK, every time....
