Do you have an M16 bolt carrier or an AR15? Going to the heavier M16 carrier might help some, as might a heavier spring.
What do you consider low end charges? I normally load 24.5 - 25 grains of Varget with the 68 Hornadys for my NM uppers. You may also try a lower charge with a faster powder, like Accurate 2460 or 2230, BLC2 etc.
One of the reasons I prefer the mid length carbines, my CAR/M4 style uppers do throw the brass pretty good, but not as bad as you describe.
I don't have time for busy people