As an old FOG, my experience is somewhat dated on actual kills; however, I will say this based on my experience in combat in Korea.
I broke my arrse making sure I was armed with an M-2 .30 Carbine with 30 Round magazines, before I had much experience with real combat.
After a few mass frontal attacks by NK and Chinese soldiers, I changed my mind and decided to carry and use the old reliable M-1 Garand, because the .30 Carbine round wasn't knocking them down. Also, in full auto-mode, most of the rounds were wasted, even turning it sideways. The old 30.6 round is hard to beat for 'knock-down power!'
When I was able to I also used the 30.6 BAR, which was my most favorite combat weapon, even though it drew fire when fired on full-auto in bursts. It did the job though!
I'd also have to give high marks to the WWII entrenching tool for CQC, when we were overrun and or/out of ammo. (As well as the .45 pistol.)
