Okay: First off, the 10mm is not the same thing as a 40. The forty is called the shorty forty because it is actually a shortened 10mm case because the full size round was beating the frames of the pistols to death and doing a job on the sensibilities of folks that fired the round. Also, the 10mm isn't what you'd call a widely available round and neither is the 40. As opposed to the 45 and 9mm which can be found everywhere on the planet and in great quanities. Maybe there is a reason for that? Anyway, that's useful in logistics (my secondary military specialty) when you run short and maybe have to make a local purchase. We used to do that all the time for various types of goods.
Perhaps the most spectacular example of local purchase is the first Gulf War when Special Forces discovered that wheeling across the desert in the HUMVEE was hazardous to your health because only Americans drove them so every sniper and jihadi with an RPG was looking for those. But in a Land Rover, Range Rover, or Toyota Land Cruiser you could be mistaken for a wandering mullah or imam and shooting at those could make you wind up in hell. So here went the SOCOM guys buying up the entire inventories of whole dealerships and screaming across the desert in these fully loaded (pun) luxury land yachts with the CD's blaring inside and the A/C on full blast.
Back on topic. The 10mm is inadequate in so many practical ways but not in the man stopping department. Too bad that's not enough. The Hague accords aren't going to change so bullet configuration is going to remain FMJ and the 10mm is far more likely to over-penetrate than either the 45 or the 9mm, bringing innocent lives into harm's way. The result is every politician's nightmare collateral damage.
Better to use a suitable platform like the USP or H&K45 both of which use a mechanical system to reduce the felt recoil. It's a DA first shot which beats the 1911 all the way around for making sure the shot is an intended action and that reduces that ~shudder~ dreaded collateral damage.
I agree with the idea of starting folks out on a 22 and working up. I use that whenever I have a novice in one of my ccw classes(I've been an NRA certified Instructor for about 20 years). The truth remains thusly: In a FMJ configuration bigger bullets are needed for a decisive stop. The round that meets the need best all around including the militarily critical area of logistics is clearly the 45 ACP.
Overpenetration? You’re a nut. Nobody cares about overpenetration from a rifle. So why should they care about overpenetration from a pistol?