The White Mountain Carbine had 2 different twists. 1 in 38, the other I think was 1 in 20 or 1 in 28. I had a .50 WMC with a tight twist and it was great on deer with 60 gr 3F Goex and green sabots with 240 XTP''s. The WMC had a half octagon half round barrel, single trigger. The Pennsylvania Hunter Carbine also had a short barrel, half octagon, half round, single trigger with a round ball twist, 1 in 66 I think.