230 gr hardball. Remember the 1911 pistol was developed specifically to knock down the Moro tribesmen in the Philippine Islands, and the 230 gr RN bullet was deemed the best round for that purpose. I don't think that opinion has changed that much in the ensuing 100-plus years since its introduction. That's what I carry in my 1911A1 today.
You're mixing up an awful lot of military and industrial history there. Round nose bullets were all that was available, in two flavors, lead and copper-jacketed. Nobody decided to go with round nose bullets, it was a manufacturing and technical reality that any pistol would be loaded with a round nosed solid bullet. Even the spitzer-type rifle bullet had only been invented what, twenty years or less earlier?
And the Army wanted what it wanted because we still had cavalry, and field-expedient euthanasia was something that had to be accounted for. On top of that, wound ballistics was a basically nonexistent field. So the bullet was what it was because there was no other option. It was in .45 caliber because that's what the last cavalry weapon was in, and the lesson learned in the Phillipines was that you need to shoot aggressive warriors more than once, not that you need a bigger gun.
I believe the 1911 was developed some years after we shot our last Moro, by the way. If the same technical, medical, and ballistics information was available to 1908, the 1911 would probably be a 15+ round pistol chambered in a round that would look an awful lot like 9mm, and we might even have a service cartridge tipped with a JHP.
Or we would end up with something like the 7.62mm M14, a weapon that is an incremental improvement over the predecessor, a cartridge that's a little closer to right, but a wasted opportunity to make some real advances.
