Very interesting. I recall relatively few offerings of police duty holsters for automatics prior to the early-1980's or so. Even then the selection was pretty limited for several years. By the late-1990's everything was turned upside down, with revolver holsters becoming harder to find and semi-auto holsters far more common. Yes, there were exceptions, some companies offering more or less, etc. The 1970's and 1980's were also years during which a number of makers offered "one size fits several" holster designs, with less attention to specific applications and fitting than has become common now.

During my service in Vietnam (1969-71) I observed the use of a limited-issue holster, primarily in Army aviation units, leather construction with snap-strap retention, open bottom, usually seen mounted on air crew members' survival vests, which would accept either the 4" S&W Model 10 or the M1911A-1 .45 pistol. I don't know the manufacturer or other particulars. Aviator's survival vests were open-weave nylon mesh with multiple webbing pouches for carrying survival gear, and holsters were frequently sewn directly onto the vests at, or just forward of, the left armpit area. Most of our air crews were issued the .38 revolvers (Model 10, round-butt or square butt, 4" standard, but a few Model 12's were also inventoried), but some of the older guys seemed to prefer the .45 pistols. A lot of the vests were "highly personalized" by individual aviators. Personally-owned side arms were seen very seldom, but some units did permit officers to carry their own handguns.

Anyway, my point is that some holsters could be used for either revolvers or semi-auto pistols, and I suspect that there was quite a bit of "one size fits several" marketing going on through the 1970's and 1980's, as US law enforcement agencies transitioned from a preponderance of revolvers to the semi-autos we see more commonly today. Some large makers catalogued their holsters as being for "Small Frame 4"", "Medium Frame 4", "Large Frame 4", "Small Automatic", "Medium Automatic", "Large Automatic", etc, with much less attention paid to close fitting or forming work than has become more common in recent years.

Thanks for an interesting post.