Military ammo is meant to be shot in vast quantities mainly to keep the other guys heads down. Chasing accuracy or quality beyond a certain point is not productive.
The average man's torso is 19.5 inches wide. Not coincidentally, so is the Army's Trainfire pop-up target. And Army TM 9-1005-319-10 says the maximum effective range of the M4 carbine against an individual is 500 meters.
At 500 meters, a 19.5-inch-wide target is ~3.4 minutes of angle in width. 3.4 MOA at 100 yards comes to ~3.6".
I don't know many shooters who would buy a sporting rifle knowing it wouldn't group any better than 3.6" @100 yards. However, from the Army's perspective, that's good enough to hit an enemy combatant at 500 meters.
And the Army's precision requirement for an infantry rifle is just that simple.
M-193 55gr ball ammo never had the problems I’ve seen with M-855 green tip.