In Pursuit of Honor

The movie is not actually based on a true story. It was based on a story that was told by cowboys to writer Dennis Lynton Clark. The cowboys were working on his father's ranch in Montana during the 1940s.

When First Sergeant Libbey shoots six of the ailing horses, he is shown pulling back the slide of his Colt .45 Model 1911 automatic pistol before each shot. When firing an automatic pistol, blowback/recoil pushes back the slide, ejecting the spent cartridge, then moving a live round from the magazine into the firing chamber and re-cocking the hammer after each shot. (That's why they're called "automatics".) Pulling back the slide after each shot will eject the fresh round out of the pistol and load the next live round, leaving every other live round on the ground. Not only does this defeat the purpose of an automatic pistol, but since the Model 1911 has a maximum capacity of eight rounds, the highest number of shots he could have fired would have been four.