We are only talking about 100 cases here, right? That's not much work or time to sort if you ask me.
I Can't imagine in a 300 Norma that your load would be sensitive to .15 gr of powder difference, which is about what 2.5 gr of brass weight is equivalent to, but the vertical induced by the increase in the approximate 6- 10 FPS caused by this difference would be about 1"
@1000 yards, worse case.
Might not make that much difference if you are in the middle of a nice, fat, velocity node, but if you're like me, and I'm guessing J E Custom, you'll want to eliminate ALL variables within your power to eliminate, and instead you'll want to be focusing on the shot and the wind, instead of thinking about the load, brass, etc.
I know guys get away with it all the time, I just haven't found myself to be one of those guys.
If it were me, I'd weight sort the 100 cases, be meticulous in all my other load prep, then shoot say 10 representative worse case weight difference of them, all on paper, 3 -5 round groups, in brass weight sequence lowest to highest, at range, on a very calm day.
Then I'd weight sort and reload exactly as before, and shoot them 1 case low brass weight, 1 case high brass weight, for 3-5 round groups on paper at range. Compare the groups. You'll have your answer.
Good luck whichever way you decide to go.
P.S. my 338 LM is sorted into 1 grain max brass weight difference per 20.