Here's a bit about LAPD guns.
From another forum, a poster mentions the line in "Onion Field" where the cop being kidnapped says to the bad guy "Could you throw our guns in the bushes? We have to buy them ourselves." Also mentioned is that one of the detectives had a S&W, one had a Colt. That was in 63, I think.
Also from another forum:
"Jack Harper, "LAPD – All Purpose Firepower", July, 1970 Guns & Ammo.
...Along with standardization of technique has come fairly complete standardization of duty revolvers. Unless an officer has had his 6-inch pistol for over two years, he must soon turn it in on a 4-inch job.
On the other end of the scale, no officer - even plainclothes detectives or those uniformed men who
are off-duty - may carry a 2-inch gun. Generally, this is to insure that an officer qualifies with, and carries, only one gun."
A buddy of mine, LAPD, had a cut down 4". That's a 6" bbl gun that the LAPD armorers cut down to 4". I think they did that in the early 70s. My buddy's gun was in 1980. It was also neutered, rendered dbl action only. I left LA before the switch over to autos happened for either the city or the county.