I am interested in a 54 caliber rifle. What is the best twist rate for the Colorado/Oregon bullet shape of two caliber length limit? Does anyone have experiance with the short conicles designed for slow twist rifles in Pa?

I have no experience with bullets designed specifically for slow twists, but have been able to shoot Maxi-balls of 370 grains successfully (2" groups @ 100 yards) from a Bill Large barrel with 1/72" twist. Remember, the Civil War Springfield had a 1/72" twist, and shot 540-grain Minie balls!