I started reading your post and decided it was one I'd have to reply as I read so I don't forget what I wanted to say.
It was JMB himself who ditched the link on the Hi Power, he was also the one who ditched his own .45ACP in favor of George Luger's 9mm.
There are other locking methods, as you say, The Beretta Storm pistol uses the rotating barrel, Not sure off hand who came up with that, but Savage used it in their 1907 .45 Trials model, Then there's wedge locking like in the Beretta 92, and the one I'm DYING to check out, the gas delayed Steyr GB. But they are all more expensive to manufacture than the Browning system.
Which is why the wonderful Steyr and SIG entries got beat by that pompous shovel making A Hole.
May hate to admit it, but no other gun on the market can surpass the Glock as a service pistol.
As for double stack Mags, the first one of those was the Savage 1907, I got one of those, a little 10 round 32. They had Bat Masterson, Buffalo Bill among other endorsements , TEN SHOTS, QUICK !
Yeah, celebrity endorsements were a thing that far back.
Cartridges, .25 Acp, 380, 45 ACP, I don't recall if JMB , the Ordinance Dept, or a combination came up with .50 BMG
Guns, Browning 1903 .380 was the US Generals pistol till the 80's, the pistol we call the 1911, Winchester 92, 94, 95 lever actions,
1917 Machine gun, 50, MG, ( 2 of those. The first was watercooled, but he up graded that when he did the .30.) 1919 air cooled MG, the BAR and the High Power.
One thing about Browning, he wasn't a "designer". He was a builder/ maker. He'd show up at Winchester with a prototype gun and after that it was up to other people to figure out how to manufacture it.
Look up Edmond Pugsley sometime . Not only was he the kid who brought Browning back to Winchester, but he was also the most important figure in the history of the BAR .
https://www.youtube.com/watch?v=OkMc8IurfAY&t=1979s