One thing to remember is that wounding a man in a western style army is probably more detrimental to unit efficiency and costly than killing him outright. It generally takes anywhere from 6-10 guys to triage, and then evac the injured soldier. If the casualty needs to be airlifted there is a risk of losing that helo, and in any event is using that asset when it might be needed for some other task as well. Losing a man outright is detrimental to unit morale and leaves a gap in squad capability, but at least few or no resources are used to further treat that man.
Moreover, depending on the standards that apply to casualty classification, it might be years, if ever before that man can return to service. My stepfather fought at Stalingrad, but was wounded by a sniper before the encirclement. He was shot in the arm, not that badly in his words (though he was decorated for his trouble). Despite this he did not return to service until June 1944, after the emergency in the west became apparent. Even so he was rapidly press ganged into the new 6A and shipped off to Rumania and finished up in Hungary (or possibly Austria….Im unsure). Point is though, that snipers bullet put him out of action completely for more than a year, and even after he returned to service he could not carry a rifle. He was essentially "walking wounded", press ganged back into support echelons as Germany went through the most acute of manpower shortages.
From a resource management point of view, it was more costly to wound my step father over killing him. Im glad that he was not killed incidentally.
A 5.56mm shell is purported to be less lethal than a 7.62mm round. Ive yet to be convinced of that, but if true, its probably a more effective weapon than the 7.62mm round from the point of view of curtailing operational efficiency, but only against an enemy that cares about its soldiers and its wounded. Against an army of madmen, intent on killing itself and fighting to the death, usually involving some form of self immolation like blowing themselves up, the shoot to wound strategy simply falls apart. In that scenario, you need a first round kill at maximum range, on a scale within the force structure. That's where the emphasis on shooting accuracy over shooting volume comes into its own, and might be some of the reason our guys have been judged the most efficient units by the (I think) US military for nearly every year of deployment since 2001.