power/vel/specs...
A number of complex issues have kept the .45acp from more duty use by sworn LEOs in the USA;
Many shooters do not like the strong recoil and more LE agencies hire small framed women/men who can't handle a large frame .45acp pistol.
The .357sig/.40S&W/9mmNATO duty pistols hold more rounds than many common LE .45acp pistols. Yes the Glock 21 packs lots of .45acp,
, but that is only 1 brand.
Power; Massad F Ayoob wrote about a documented LE shooting in Texas where a new DPS trooper fired his issued .357sig into a truck cab and ended an assault. The young trooper's senior partner had a SIG P-220 .45acp and the rounds did not punch through the metal,
. .45acp rounds are big slow and do not go as deep as the .357sig/.357mag/.40S&W. That is another reason that .45s are not in use.
Finally, the .45acp is used mostly in the 1911a1 pistol. It's single action and requires a highly skilled person to carry/use it. Many SWAT/spec ops carry the big 1911a1s but they also train, train, train...
. A DA only or DA/SA .45acp is far safer for most LEOs.
Rusty S