1959 Change extractor rod, right hand to left hand thread 15–2, 1961 Delete trigger guard screw, change cylinder stop 15–2, 1964 Introduce 2” heavy barrel 15–3, 1967 Relocation of rear sight leaf screw 15–3, 1968 Delete diamond grips 15–4, 1977 Change to put gas ring from yoke to cylinder; pinned barrel eliminated 15–5, 1982 15–5, 1986 Introduction of 6” and 8-3/8” barrel 15–6, 1988 New yoke retention system/ radius stud package/hammer nose bushing 15–6, 1988 Discontinue 8-3/8” and 2” barrel 15–6, 1992 Discontinue 6” barrel, blue finish only 15–7, 1994 Synthetic grips introduced, drill and tap frame, change rear seat leaf, change extractor 15–7, 1995 Delete square butt 15–7, 1996 Begin shipments in blue plastic case 15–7, 1997 4” barrel only; change to MIM thumbpiece; shipped with master trigger locks; change to MIM trigger 15–8, 1997 Changes in frame design: cylinder stop stud eliminated; eliminate serrated tangs; change to MIM hammer with floating firing pin and change internal lockworks 15–8, 1999 Model 15 discontinued in November 15–8, 2001 Limited run Lew Horton Heritage Series from the S&W Performance Center. 15–9, 2002 Limited run Lew Horton Heritage Series McGivern Models from the S&W Performance Center. 3 Models commemorating Ed McGivern's world speed records in 1934 with a revolver. All models have a Patridge front sight with Gold Bead, round butt frame with Altamount Fancy checkered service grips of that era, 6” barrel, Ed McGivern commemorative plate mounted on right side of frame, Heritage Series box. 15–10, 2011 Reintroduced in Classics Revolvers line, re-tooled, shrouded redesigned barrel, internal trigger lock. Discontinued in 2013. Military and police usage As the "K-38 Combat Masterpiece", this revolver was first purchased in 1956 for the Strategic Air Command Elite Guard of the United States Air Force. From 1960 to 1969 the Air Force bought large numbers of Model 15–1, 15–2, and 15-3 revolvers with a 4" barrel. The only distinctive markings are "U.S.A.F" on the left side of the frame. Originally all were blued, though some were reparkerized while in Air Force service. The Model 15 was the standard issue sidearm of the U.S. Air Force Air/Security Police from 1962 to 1992. It was issued to security personnel in other branches of the U.S. armed forces, including the Naval Security Forces. The Air Force issued two types of .38 Special duty ammunition for the Model 15, originally the M41 .38 Special Ball (full metal jacket) cartridge,