The US military had three service pistols widely distributed and used by all branches in modern history. First, to be clear, US military service pistols are mostly made for self-defense. The only way a pistol works as a defensive weapon is if you are an expert on the Combat Qualification course. The pistol is your secondary weapon and a backup.
There are three US military service pistols everybody heard about:
Each pistol represented state of the art (more or less) when purchased initially. The Colt 1911 is from, obviously, 1911. Compared to its contemporaries, it’s easily the leading pistol of the era. In 1984, it was hard to argue that the Beretta 92FS wasn’t the best of guns submitted for testing. (Note: Glock did not bid or provide a pistol for that test).
There is no stock trigger on the market that outperforms Colt 1911. At least none that I’ve handled. Overall these are supremely smooth shooting guns, and they’re always fun to shoot. Now for cons. They have a very low capacity. Even though you can compensate for it, some with quality hollow points in the civilian world. We can’t (Geneva conventions and whatnot), so the difference between 9mm and .45 isn’t enough to cut capacity in half.
Then they’re big, heavy, steel guns. Ounces make pounds. In a military application (army/marine infantry specifically), a pistol is rarely used and thus doesn’t warrant carrying the extra weight in an all-steel design. Lastly, there are safeties, and it’s a single action only design.
I don’t want to have to think about flicking off a safety or pulling a hammer back when I’m already at a point where I’m drawing a damn pistol. I don’t want to have a hammer cocked all the time, adding to the list of bs to get caught on everything while I’m trying to move through a house-in kit that already makes that a pain in the ass. Again, I love 1911 to death; I just don’t think it’s the best choice for a combat handgun today.
M9 (Beretta 92FS)
The M9 is a superior weapon. Five rounds of 9mm per mag and fewer parts/easier to field strip and clean than 1911, but that’s about as far as it gets advantage wise IMO. This thing is incredibly bulky for a pistol, especially a 9mm. The design is very open, good for weight but bad for when you fall in the mud and need it right now.
I like that it’s double to single-action, but the way the safety works is probably one of the least intuitive or ergonomic designs I’ve ever dealt with, and it sucks to operate in gloves. Aside from that, they shoot pretty well in my experience.
M17 (Sig Sauer P320)
And in 2017, it’s hard to argue that the Sig Sauer entry (as the M17) wasn’t the best one. (Note, it has some differences from the P320). And each of these is a major step forward from the prior issued pistol. Compared to the M9, Sig Sauer P320 can be configured for different missions and have a rail on which accessories like lasers and optical sights can be mounted. With an extended magazine, their standard capacity of 17 9-mm rounds can be increased to 21.
Part of it is simply that guns are mechanical devices that wear out and fail. Part of it is that the military cleaning process beats the shit out of guns. Part of it is that time marches on, and new innovations happen. The idea of things like mini red dots and true modularity is, well, new.
The Colt 1911 is heavy, sturdy, and well built. It is also old—over 100 years. The Beretta is much newer and has improved technology. The Sig is still more recent and has some changes in it.
Personally, I very much like Colt 1911. It’s a shooter’s pistol. But that doesn’t make it a good pistol for the issue. It’s the ’57 chevy of pistols. Great if you are a car guy. But if you want reliable transportation to work, it’s a horrible car. Get a Toyota Corolla. The M9 and M17 are Toyota corollas, which is exactly what they should be.
The Beretta/M9 was safer than 1911 because it was double action and had a hammer drop safety. Too many could have an AD with 1911 if they don’t practice it.