USAF was the first to adopt the Colt/ArmaLite AR-15 in significant numbers, wonder why they didn't also adopt a modern 9mm semiauto pistol like the M-39 to partner with the AR-15 in the 1960s during the Vietnam War for combat Security Police squadrons? US military still had loads of S&W and Colt revolvers left over from WW2 and Korea for those needing a revolver like pilots and dog handlers. My USAF base armory had Colt Det. Spec. that were liked for courier and base finance office duty. The M-39 would of been the perfect compliment to the the AR-15 and light years ahead of the other US services.