1:12 is a no go on them. 1:9 minimum twist rate for the 75's. I have a 26" 1:8 McGowen and shoot the 80's to 3220 with 35g of Power Pro 2000MR. Ring steel at 1000 yards with only 28 MOA of elevation. Headshot a doe at 220 yards with it. 22-250 with the heavy bullets is a great combo but you do need the barrel twist to get there.