I don't remember Edmund O'Brien's character "Freddie Sykes" carrying a Winchester 92 in The Wild Bunch. In the scene where they return from the botched job in the fictional Texas town of Starbuck after escaping the ambush, and the Gortch brothers are complaining about the shares, O'Brien is shown pulling an 1874 or 77 model Sharp's rifle from a scabbard and cocking the hammer. He's also shown carrying this gun when he's ambushed by Thornton's posse while on horseback and is hit in the leg or hip.
In the movie The Killers, O'Brien's character Reardon carries a Colt Pocket Hammerless, either 1903 or 1908, and loses it when attacked by "Dum Dum". He asks a police detective he's met if the cop brought "an extra .45", and the cop replies "yeah, what happened to yours?" a reference to the Pocket Hammerless which was never made as a .45. However, when Reardon is next seen with a gun, when he's attacked by the two killers from the begining of the movie in a restaraunt, he's holding a snub nosed .38, not a .45.