Regarding the Colt question, the 4” Colt Police Positive Special was standard issue for agents when they were first each permanently-assigned a handgun in 1933, supplanted by the 4" Official Police by the late Thirties. In October 1934, Melvin Purvis fired his Colt Detective Special at Pretty Boy Floyd and missed him with all six shots. [At 60 yards. I have long wondered why stage 2 of the original PPC started prone at 60, instead of 50. Perhaps it has its roots in this incident and the expression, “Don’t embarrass the Bureau!”]
The Colts started to fall out of favor when double-action shooting beyond 7 yards was implemented and became common in the Fifties. In the early Seventies, the Bureau adopted the 158 gr. LHP +P (St. Louis/Chicago/FBI load) as its new Service round and asked the manufacturers about using this ammunition in their guns. As I recall it from third-hand reports outside the Bureau, Colt initially equivocated before eventually giving a conditional yes. Unsatisfied, the Bureau decided to recall from the Field all the issue Colt .38 revolvers.
[Sadly, the 1934-circa Super .38s in my old office’s vault were sent back to Quantico with all the Colt revolvers in response to this edict. Either the PFI didn’t know what he was doing (“Hey Bob, it says Colt .38 right here on the slide of this old gun”), or he did (“Hey Bob, let’s slip in these old .38 autos so we don’t have to inventory them every year anymore”). I always wished I had had a chance to shoot them to see if they would stay on the Colt Silhouette at 60 yards. Somewhere I have read that some Colt specialists suggest that high-end pre-war Supers didn’t show the accuracy problems that plagued later specimens due to inconsistent head-spacing on the rim.]
A number of the Official Police revolvers were later returned to the Field as deactivated non-firing “red-handles” which were used as prop guns for training exercises. At the turn of the century we had one older agent in our office who still had a Colt Detective Special on his POW list. He must have gotten it approved a quarter-century prior, just before the recall. He didn’t qualify with it or carry it on duty to my knowledge. In the wake of the lost guns and laptops scandal of 2001, the Bureau got a little more religious about purging the POW lists of any guns that were not qualified with annually, and the old Colt officially vanished from the rolls for good late that year. That was the last operable Colt revolver I ever heard of in the Bureau outside the FBI Lab.
Oops -- I had forgotten that they had Hoover’s issue 1937 3” Colt Pocket Positive .32 with bobbed hammer in a display case at the Quantico Gun Vault a few years ago and it is probably still there. No obvious signs that it had been deactivated. I think these were very rare. The late Larry Wack’s Dusty Roads website shows Tolson owned a POW Colt PP .32, also dated 1937, and that Hoover owned a presentation model 2” nickel POW Colt PP.32 with bobbed hammer dated 1938. The internal inventory of original Buguns on hand when the War on Crime began, also set forth on that site, shows that there were two additional .32 caliber Colt revolvers located in the San Francisco office in 1933. Make of all that what you will. A relative of mine had long-standing good service from a Smith M31-1 in .32 Long, so I kind of like the 6-shot .32 caliber “Hoover Special.” I think we can conclude from the above that any small-frame six-shot .32 with either a 2” or 3” barrel can legitimately be termed a Hoover Special. I wouldn’t mind having a Smith M432 myself someday.