Slight thread deviation: Tonight I fired 150 rounds in my new-to-me 3953, actually a bit of a beater, a former "N.P.D." gun. Very accurate and easy to handle; 100% reliability. Still not sure how it affects the muscle memory needed to use the 3913 well, but lots of fun to shoot. The DAO (without re-strike) function seemed a bit strange at first but works like a charm. So, its off to the gunsmith for a bead-blasting of the slide, not to make it like new, but to make it look better than it does after many years of being carried in somebody's holster.