I have made a .308 barrel for my .457 Texan but just get "tank dumps" each time. The possibility is that the hammer /spring tension is too heavy for the smaller calibre & lighter 130gn to 220gn cast lead slugs regardless of tank pressures under 3,000psi. My only course is to make a set of lighter/shorter length hammers to see if the dumps stop. Has anyone measured or weighed the hammer on their .308 barrelled Texan? I do not think the top hat holes are too large or the spring tension even on the lightest wheel setting with pressures between 1,500 & 2,500psi. Tank dumps every time. After replacing the .457 barrel things go back to normal regardless of pressures. Luckily it only takes a few minutes to swap barrels.