Interestingly, the Salt Lake City (UT) P.D. switched away from the S&W Model 39 9mm semiautomatic pistol and "backwards" to the S&W Model 64 .38 Special revolver in about 1978 or so. The department had a couple of "unintended discharges" with them that were variously blamed on the pistol design and/or the instruction in it's use provided by S&W. One of the accidents resulted in the tragic paralyzation of an officer who was on a surveillance detail when he or is partner (I forget which) placed their pistol on the dashboard of the van they were in and it went off.

One of my neighbors was a patrolman with SLCPD in those days and I used to ride along occasionally with him on graveyard shifts while a college student. He wasn't a 'gun' person and always disliked the M-39. He had several 'unintended discharges' and stoppages during qualifications, including at least once when he was holstering it, claiming he had his finger nowhere near the trigger! The department would issue him a new one each time he had a problem; I think he went through 3 or 4 at least during the time. He had just been issued a brand new 39-2 when they decided to replace them with the revolvers. He was happy to see it go.

I could never understand how he had them go off without the involvement of his trigger finger. I think he might have been a little mistaken there, but...

I have had several, all -2's, and while I never put a really lot of rounds through any of them, they all worked quite well and were an easy pistol to shoot. They, and the double-column magazine Model 59, were really pioneers of the American law enforcement move away from the double action revolver.