Back in the day the standard carry for a LEO was the .38, followed later by upgrading to the .357. Then came the semi autos, in various calibers such as the 9mm, 40 and 10. What ever happened to the .45? With various agencies you find various calibers, although now the 40 seems to be most popular. Question. Why didn't the .45 become the default cartridge for all LEOs and their agencies? Its been around for a long time and is a proven man-stopper. If I were back in uniform and had to carry a semi-auto it would be my first choice.
Sir, as far as I can tell, it's a strange web involving lots of things having nothing to do with what's best for the cop on the street.
Some of it's gun types. Back when the switch from revolvers to autos was gaining steam in the early '80s, the 1911 was about the only .45 auto commonly available. Unfortunately, a lot of police/municipal "powers that were" at the time were afraid of it. They thought it kicked too much and were downright alarmed by the concept of "cocked and locked" carry. Some still think this way today. The 1911 was also expensive, which didn't help.
So they largely went with DA/SA 9 mm autos, a number of which could be had from their old friendly suppliers at S&W, which was a plus. And so the powers were happy for a while, though Jeff Cooper scoffed about "crunchentickers."
In time, the 9 mm had a number of well-publicized failures, probably the most famous of which was the FBI's Miami Shootout. Whether the failures were problems with the 9 mm itself or deeper problems (poor marksmanship, bad procedure, insufficient training, ad infinitum) remain hotly debated to this day.
So anyway, perceptions about the 9 mm changed, and it was no longer deemed sufficient.
The FBI did a bunch of well-publicized tests (in which the .45 ACP fared quite well, BTW) and concluded that a light-loaded 10 mm was the way to go. Trouble is, the 10 mm requires a .45-size gun (many of which at the time were still 1911s--see "scary 1911" comments above), and which girls and little men presumably will have problems with. Oh, dear, what to do?
Along comes the .40 S&W, which just happens to ballistically duplicate the FBI's preferred "10 Lite." It fits in 9 mm size guns that aren't scary 1911s, and it isn't a sissy 9 mm or a primitive .45. Woot! The powers and the street cops all are delighted. Never mind that the .40 is harder to shoot well than the 9 mm (or the .45, for that matter) or that the original 9 mm size guns had to be beefed up substantially lest they take themselves apart at inopportune times.
Then along comes Gaston Glock with his marvelous inventions. They're cheap, reliable, accurate enough for people who don't shoot much (i.e., most cops), and cheap. Did I mention that they're cheap? Police/municipal powers again are delighted, street cops less so initially, but in time they warm up to the Glock. Eventually, the Glock becomes
the gun, and anyone not shooting one is either a caveman or a dithering idiot. Never mind that Glock .40s blow up with some frequency or that even the smallest Glocks are great fat things that require longer than average fingers to grip well.
So we've ended up with an odd little high-pressure Goldilocks cartridge in a lowest-bidder gun that doesn't fit the small hands it's supposed to be intended for and that kicks like a much bigger gun. Contrast that with the old .45, a well-proven cartridge with easy recoil and that's now more effective than ever, available in a trim gun (1911) with a nice trigger that fits most hands out of the box and can be readily changed to fit others at either end of the scale.
Apparently the .45 just makes too much sense. Does that answer the question?
(Tongue in cheek here, but only a little.)
Hope this helps, and Semper Fi.
Ron H.