I read a good explanation in laymens terms. Smith and wessons internals operate straight forward and make sense. Colt on the other hand has internals that work completely backwards in the mechanical thought process, as the opposite way one would think makes sense. Maybe the reason it is so hard to find anybody to work on Colts now days. The cylinders turn in on Colts and was once thier selling points in the strength of the lock up. Smith & Wesson cylinders turn counter clockwise. They are just two completely different animals.