Years ago my dumfuuk liberal uncle claimed that the Viet Cong could use 5.56/223 ammunition in their rifles.
Unlike during WW2 when we could use the German’s ammo in our rifles. I was a teenager at the time and had been taught to not publicly disagree with adults, but it was obvious to me that he didn’t know his azz from a hole in the ground.
A not uncommon thing to hear around SEA during my time over there was that the AK47 used the same ammo a the M-14, an idea spawned no doubt by the fact that both are 30 caliber.
