That's a good group for a pistol and factory loads...at 50yds. You did mean 50yds....right? not 50 feet? The overall length of a .410 shot shell can be up to 3" (3" magnum). The over all length of the 45lc is 1.6". Seems to me, a cylinder that would accommodate both would mean the 45lc bullet would have to travel at least .5 inches before it reaches the barrel. Magnum Research indicates the barrel is cut rifled, so the head space for that colt round is like up to 1.4" as the gun is chambered for 3" shot shells. That is excessive. It does not seem to hurt the accuracy, based on your groups.