1" and 3/4" groups at 100yds is insane for a slug! that's awesome, I'm getting a 220F when I can!
I thought I read somewhere that the rem accutips were designed for the slower twists of the rem barrels, etc...something like that, but I think that was in relation to the 12gauges, I think there may be more variance in the 12's than the 20's, in regard to twist rates.
13" of drop from dead on at 100 to 200 doesn't seem that bad to me, bullets drop, and slugs going 2000fps are a big difference from bullets going 3000+ fps
how good are those groups at 200? even if you could get good groups at 150...