Not sure what your first point is meant to be since I basically said "untrained+SAO=carrying hammer down (regardless of whether or not chamber is empty)", and that for a SAO handgun you have exactly 2 options, of which one might not like either, as compared to the plethora of ergonomic options with DA/SA (and now striker guns but I was more talking about BEFORE they became so ubiquitous)

The US Army is indeed slow, but if the money had been there in 1955 (remember, the Korean Armistice had just been signed so the US was just coming out of a war, and the M14 was just then being adopted, among other new, costly, developments), there's a good chance there would have been a switch to a 9mm DA/SA, be it the S&W X100, the Colt T4, or the High Standard T3, the impetus for this being the Walther P38. From everything I can tell, though, from WW2 to the end of Vietnam, it really seems to me that anyone that could had a DA revolver or DA/SA pistol, then out of those remaining that were issued sidearms, a significant amount were plainly issued a .38 DA revolver (Colt, S&W, Ruger later on). From 1947 all the way through 1985 adoption of the M9, every time the US military looked at new handguns, they were to be 9mm; I don't think it was specifically to appease NATO.

The 5-6 shot comment refers to the fact for most of the previous century, if you did not want a single action pistol, your options were either a 5 or 6 shot revolver OR a DA pistol. You forget we're not just talking about military sidearms, but also those of the police, who in the US went DA revolver->DA/SA pistol->striker, with most private duty pistol purchases being DA revolvers and DA/SA pistols (such as the Beretta 92 series, S&W 2nd and 3rd gen autos, Ruger P series, and SIG's P22x series) before striker fired guns dominated everything.

You can't really consider a gun ready to fire if you have to take additional actions to make it shoot, past pulling the trigger. Also keep in mind the 1911 in military service always had a small, easily missed safety, and the BHP was generally carried with nothing in the chamber and the hammer down. I don't think that really counts as "ready", especially under stress or if you need to be quick. At least with a (military, semi auto) rifle, the safety is usually big and/or doesn't require you to shift your grip at all. And with a DA/SA, decocking is done as part of loading the gun, and can be skipped if you're reloading during a course of fire/combat, as opposed to having to be done after drawing, before you can shoot

It's disingenuous to say that DA/SA pistols have to have the safety removed to fire since you are not intended to carry them with the safety on; the safety on a DA/SA is only for decocking and storage, unlike an SAO, for which it's required if there's a round in the chamber. As for safety-less DA's besides the SIG not having been adopted, the HK offerings with LEM triggers, Walther P99 and PPQ, Canik whatevers in use by Turkish police, and the Beretta 92G beg to differ.

To put it in plain English since you seem to think otherwise, DA/SA PISTOLS ARE MEANT TO BE CARRIED ON "FIRE", ROUND IN THE CHAMBER, HAMMER DOWN. Just because the gun goes on Safe when decocking doesn't mean it's supposed to stay that way, you put it on Fire before holstering. To assert otherwise would be like saying you should carry a revolver with the hammer back just because it's possible. Just because you can, doesn't mean you are meant to or even should

DA/SA is super easy, all you have to do is decock and put the gun back on fire when you load it, which takes less than a second and generally has a HUGE button or lever to do so. As for the first shot being a little different, that doesn't really matter all that much, and if it throws someone off they still have 7-20 rounds in single action to put into the aggressor. In any case, if someone can't handle that, they're probably not going to be able to handle remembering to take the gun off safe as they draw (SAO), reloading with a speedloader under stress (revolver), learning trigger discipline (all, but most important with striker guns based on how often people ND them), or unloading the gun before pulling the trigger to disassemble (striker). And for people supposedly well versed with handguns, if they can do any of the above but not learn how to operate and shoot a DA/SA, maybe they're not nearly as well versed as they thought (see: 9/10 people that complain about DA/SA, slide mounted safeties, polymer guns, anything that isn't a 1911) and would benefit from a trip to a range that rents handguns just to familiarize themselves with guns different than what they prefer.

TL;DR: just because it isn't a Glock or 1911 doesn't mean it's bad, go shoot different guns

All this being said, I personally like the P320 better than the Beretta 92

I think had the US Army not had their budget gutted post WWII, they would have been getting new 1911s instead of keeping the old ones in inventory until the 80s. There's accounts that the 1911s were in rough shape and that was one of the deciding factors to get a new one by the 80s. They could have easily adopted the Browning Hi-Power like the British but like with the FAL vs the M14 thing, America wanted to be "different" and Beretta won that contract anyway.

The 1911 still is the longest service sidearm in the US military and it was hard for the old school to abandon the .45 caliber in favor of 9mm. It was a political choice to go with the "new" DA/SA design

I highly doubted the US Army would have adopted the Colt T4 since it had no trigger guard.

It used a fold-down trigger guard.

http://securityarms.com/20010315/gal.../2900/2904.htm

There are a lot of people in high places who expect a "peace dividend" to be available after every major conflict where funds can be diverted from the armed forces without compromising their abilities to other ends. As the Korean War and the Vietnam War proved after WWII, peace doesn't often last.

The US Army could have done a lot of other useful things too, such as adopting the British .280 cartridge as a good General Purpose Cartridge, sparing us the "golf bag" approach with 7.62mm NATO and 5.56mm NATO.

You know, except for the fact they explicitly set out to replace them with a 9mm, with continual efforts to do so starting in 1947, and only didn't because of budget constraints (IIRC it came down to one brigadier general's decision, and he decided not to proceed due to cost, in favor of replacing the 1911 when they wore out, which I think was expected to happen sooner rather than later since they were basically disposable and weren't even fully heat treated). Not that all the potential replacements were DA/SA, as the earliest efforts were why the Colt Commander (in 9mm) was developed


I love 1911's, but they weren't the best they could be until post WW2, when Colt started making the Commercial 1911's using fully heat treated, forged steel. Before that, peening (pre A1) and cracking (A1) were a known issue