With all due respect, Colt most certainly did use the Swartz system from the late 1930's until commercial production ended for WWII. Even the 6,500 pistols transfered to the military contract from commercial production had the system. Colt removed the parts but the Swartz cuts are still there. Same with many of the guns shipped to Latin America. Colt let the patent expire in the 1950's and designed a new system for the Series 80 guns.