Not to be disagreeable but I disagree. There is such a thing as knock down power - it’s best representative is the .45 ACP round. It was designed to specifically put down drugged up asian muslims who used hemp rope as torso bullet protection. The round did exactly what is was designed to do-put down bad guys fast. The round saw real world testing from Phillipines, WWI, WWII, Korea, and Vietnam. The first time we had close combat with the 9mm in room to room engagements we had problems (7 to 9 hits to enemy personnel before they were down). Two rounds, similar size, big difference in effect due the speed of rounds; 9mm supersonic, .45 subsonic. Likewise with 5.56mm. when we weighted it up for SAW and added more propellant we got ice picks at short range. The original specs on 5.56 represented a very light round with an effective range of 300m max. By design it was supposed to tumble when entering flesh, thus causing a larger wound channel. As we added weight to the round (first to improve rifle range scores at 300-500yds, and second to use as a machinegun round at 700m) and propellant we lost the designed tumbling (instability) properties of the round. Thus it lost its knock down power. See cavitation and bleed out rates. Or just go read the 1930s Pig Board report. This is a recurring conversation with Army/Marines, the argument always ends with the recognition of the size of our ammo war reserve quantities and cost to change round/rifle. Personally, would prefer a 6mm or 6.5mm round for combat, but we are stuck with 5.56mm for a long while.
If the human body were a steel plate, and absorbing the energy of the round was the only factor, then “knock down power” and the resulting calculations would be the end of it.
But taking a person down is more about placement and the resulting organ, CNS or bleed out than the mass of the larger/slower projectile.
IIRC, the one-shot-stop statistics between .45ACP and 9mm were within 5% of eachother, with the .45ACP getting the edge.
The adoption of the SAW and the M955 preceded the M-16A2. We got the additional range for the SAW, then the USMC project team came up with a revised rifle to chamber and accurately fire the 62gr bullet. What we lost was the fragmentation (and the larger permanant would canal) that the thin-cannalured M193 provided (upon initial yaw/tumbling).
Agreed, logistics are what keeps any new cartridge in the “wishful thinking” stage, but logistics is also what ensures that we have a shitload of ordnance.
And, disagreeing isn’t necessarily “disagreeable”. We haven’t resorted to name-calling.
yet ;)