I have never seen a 10 bore Baltimore Arms gun, nor can I find any advertising for one .. The 1900 catalogue states 12 bore only, with Twist, Damascus, or Fluid Steel.. Later advertising offers !2 and 16 bore, with Fluid (Krupp) steel,, However, I have found that there is really only on rule for vintage Americam Doubles, and that is the fact that there are no rules..JFC
