Posse From Hell is a 1961 Western starring Audie Murphy, Lee Van Cleef (whose bad guy character you see early but not again 'til the end), John Saxon (a favorite from science fiction and horror films, he is still active) and Vic Morrow (killed during the filming of Twilight Zone: The Movie). Also here are Rodolpho Acosta (Vaquero in The High Chaparral), Royal Dano (Casey in The 7 Faces of Dr. Lao), Frank Overton (Star Trek: The Original Series), Paul Carr (ST:TOS) and Allan Lane in his last film (he voiced Mr. Ed in the TV series).
This is a traditional western with bad guys who are very bad and a useful woman who gets in the way. And it has Lee Van Cleef (which is reason enough to watch any film). But if Audie Murphy talks any more about "riding these horses to death" I may scream.
TCM has an overview. I don't see many reviews.