The action film is a pretty obvious genre. It's purpose is to distract, entertain, and many money. Yes, there's quite a market for this material, probably supported by a similar audience that keep gothic paperbacks moving in the marketplace year after year.
"100 Rifles" is a substandard action western that offers a time capsule back to the late 60s early 70s. Generally unpleasant in its excessive depiction of killing and bloodletting, the film does utilize the star talents of three interesting actors.
The lead role gave Jim Brown an opportunity to strut his macho stuff, riding horses, shooting bad guys, and fist fighting his male costar on occasion. It also provided a couple of intended heated love scenes with his leading lady. Unfortunately, Brown comes across as wooden and even disinterested here. Too, his vocal instrument is much too high pitched and unsonorous to match his impressive physicality.
Burt Reynolds comes off better, making the most of his high cheekbones and sunken eyes--lending credibility to character ethnicity. He, like Brown, is in fine physical shape, and even elects to do some fancy stuntwork himself, like jumping off a moving train.
Still, it's Rachel Welch that emerges victorious here. Here's an actress that takes on a routine part in a routine script and plays it for all its worth. Also in great shape, Welch knows that if she's got it, she might as well flaunt it. She does, and we are the appreciative recipients.
The film also shows how much energy it takes to do this kind of production. Not a great deal of brainwork required, but a barrelful of brawnwork.