Im using a 1-20 and 1-22 twist 45s. Ive already ran the stability estimates and its fine even with medium loads. The 40-250gr is .998" long. JBM says its fine even at 1800fps in a 1-22.

Bore Butter will never touch my barrels ever. I never seem to have any issues igniting BH209 in my rifles so i cant imagine how putting anything on the powder side of a sabot will help. 250gr for a 40cal is pretty heavy and my bores are not loose. Ignition even with smokeless in the SavPac should be flawless.