In the Rifleman many years ago, a match shooter did an article on brass. C. Audet I think. Commercial and "match" military brass was about equal. Comparable. Range run mil. surplus brass was of less consistency.
I pondered that until I had a dear friend who had trained as a WW II aircraft gunner tell me about it. He said that the trainers said they wanted dispersion, like a shotgun firing pellets. It was unavoidable in a reasonable weight gun so they used it. Called it "cone of fire." Point is that the barrel will not be in exactly the same place each time a bullet leaves the muzzle. So a "burst" will spread like a shotgun pattern. I came to wonder if the inconsistency in standard military ammo might also be influenced by this. No doubt, it is also cheaper to produce to this lower standard.
ii). Obviously, the slamming of full auto is also harder on the brass and a reason for a "sturdier" case.
#2). If you are "working up a load" safely, what does it matter. You start lower and seek accuracy or prohibitive pressures...
Retired gunsmith friend had a story about the .243 Rockchucker (like .244 Remington but more shoulder angle)... He got his best accuracy from reformed mil surplus brass which held about the same charge of powder as a .243 WCF which became factory. So he gave up on the wildcat and got a .243... Your bucks, YOUR RISK, your call... luck...