BTW: As for stopping a horse?
That was probably very true when the .45 Colt SAA was adopted in 1873.
Not so much a factor by 1911 with horse solders on the way out and WWI on the horizon.
In fact, the Cavalry was the functional proponent for the M1911 -- one reason it has both safety lock and grip safety, to make for safer handling on horseback. In 1911, no one had any inkling of what WWI would be like -- many European cavalry units were armed only with sabers or lances. Europeans though giving them firearms would detract from their
real combat role, the charge with white weapons.
Hard to imagine the velocity-cursed .45, penetrating enough horse to drop it.
Nevertheless, it did.
I know the guy who restored General Pershing's 1916 Dodge Touring Car, which he used during the Mexican punitive expedition. He did not know the story of Patton and that car until I told him -- then he called a buddy at the Library of Congress, and got copies of the orginal newspaper account, complete with photographs. He displays this with the car.
Patton was sent out to contract with local ranchers for hay. While tooling around, he heard a rumor of some Villanistas at a nearby hacianda, so he went out to check.
The Villanistas were there, with horses saddled and bridled in the courtyard. They heard him coming. Their plan was to let him pass and slip out and go the other way. Plan B, if he stopped, was to wait until he got out of the car, then ride him down.
Patton pulled up, got out, and suddenly the gates of the hacianda banged open and three mounted Villanistas came galloping out, whooping and shooting. Patton, armed with a Colt SAA, but using ammunition ballistically identical to .45 ACP, killed the lead horse. The other horses went down over the carcass, and Patton shot all three Villanistas.
He came driving back to Colonia Dublan with the highest ranking Villanista tied to the hood. The picture shows the dead man astride the hood, facing the windshield.
Yes, the .45 will indeed kill a horse.