This is described as taking place in 1866 - two years after the War Between the States. The weapons used are anachronistic. The first Winchesters were made in 1866 and certainly not enough to have populated the 'West' so rapidly as to be the dominate arm in the movie. And the Springfield trapdoor shown in the movies wasn't around until 1873.
However, only the opening scene is set in 1866. The rest of the movie is set 22 years later in 1888. By then these weapons would have been available and commonplace.
However, only the opening scene is set in 1866. The rest of the movie is set 22 years later in 1888. By then these weapons would have been available and commonplace.