I believe (my books are in storage while remodeling) when Saive stepped in, the Browning design had a striker and when the Colt 1911 patents expired in the late '20s, Saive incorporated the Colt barrel bushing design, the Colt locking system replaced the breech bolt and the Colt takedown system was incorporated. The barrel bushing morphed into the fixed bushing we see now sometime in the early '30s. Saive added the curved backstrap. The slide was shortened and slimmed, and the magazine capacity was reduced from 15 to 13 to meet weight requirements.