I understand it is difficult to drill a uniform hole down a blank piece of steel. If this is true why don't they (barrel makers) routinely make larger calibers out of previously smaller ones? Is this due to some tooling/machining difficulty? For clarification: barrels that have been shot. Is this done in the shop on barrels that haven't been tapered/chambered and/or shot? Is it due to liability...not getting the same barrel back or one someone tried to stress relieve theirselves? Is it just not economical? WHY do you ask? I don't really know.