From the OP...
So I'm wondering - what do others consider to be the standard service calibers for handguns.
Why is "common" based on a seemingly random matter of my personal knowledge? Why not? This is an opinion-based thread, and I've personally researched a few dozen police and sheriff departments in probably ten different states over the last few years. Without referring back to any information, and going off what I recall, .40S&W absolutely stands out as the #1 issued caliber among law enforcement in America today.
It's interesting to see what folks are listing and when and how they place a cut off. It's both by age of the individuals and personal experience it seems. And also by how much studying one has done.
Some folks mention the 45GAP, an oddball round that I'm not sure is used by more than a handful of law enforcement agencies, if that many and is only chambered in Glocks that I know of.
A service caliber round in handguns is a round that has been issued for duty carry (not for training or trials) by a law enforcement agency or the military on a widespread scale. It was issued "for service" meaning as a
primary carry round in a sidearm. This means it is not so much a matter of "opinion" but is a matter of research and deciding what the cut off dates will be.
The U.S. military used to issue the Colt M1903 and M1908 pistols in .32acp and .380acp to officers for several decades. So technically those rounds could be considered service calibers at least at that time. In Europe and Japan those rounds were most definitely service calibers. But not now. That some cops may carry them as backup does not count.
The 22 L.R. has been widely used for training in the military (and sometimes survival guns for pilots) and some police depts. But that is for training and it is not and never has been a service caliber because it was not a primary carry round.
The 45acp is still issued in the military (on a small scale) and is still used in law enforcement across the U.S. Less than the 40S&W and the 9mm but it is still authorized for carry. So it remains a service caliber.
45 Colt was a service caliber and distributed widely and can still be considered one depending on the dates set of the discussion.
The 44 Mag and 44 Spl. may have have been issued here and there to individuals but never saw widespread issue in the military or law enforcement so have never been service calibers.
The .357 Magnum did see widespread issue and remains a service caliber.
The .38 Spl. remains a service caliber.
The 38 long Colt and the 38 S&W were at one time service calibers but have not been used for about a century as such.
The 38 Super saw some service but was not widely distributed enough to get the nod, at least not in the U.S.
Anyways, some thoughts.
tipoc