As with so much of the output of legendary producer Dino Di Laurentiis (whose movie industry nickname was "Dino Di Horrendous"), this is outrageous, overblown seventies tosh. Apparently it was supposed to be a Western version of "Jaws", and a rampaging buffalo was the largest and deadliest creature cowboys might plausibly encounter. And of course, it had to be not just any buffalo, but a great white one like the shark.
Naturally, the elephant in the room is the white buffalo, which had to be realized using whatever methods existed before CGI. Stephen Spielberg famously had no end of trouble getting his animatronic shark to look lifelike, and he had it easy. Sharks are fish, with no legs, no fur, and totally immobile faces, and they spend most of their time conveniently hidden underwater with just that distinctive dorsal fin showing. A buffalo is a much more complex beast to animate, and the example we repeatedly get a very good look at in this film is hilariously unconvincing, not least because when it charges, its lolloping gait suggests one of those mechanical animal rides shopping malls provide to amuse very young children. In fact, one surprisingly lengthy shot clearly shows that its hindquarters are a cart running on extremely visible rails.
Up against this ridiculous and seemingly supernatural beast, the nature and purpose of which are never explained, are Wild Bill Hickock and Crazy Horse, two real people in a completely unreal situation, which isn't helped by the incredibly strange dialogue. Everybody who isn't a Native American talks in what can only be described as "cowboy Shakespearean", meaning that they constantly come out with utterly weird lines that are sometimes downright incomprehensible. All this while hunting an absurdly fake robot buffalo which is apparently both a Native American evil spirit and a Christian demon, and amongst its superpowers, can cause avalanches by roaring, something it does frequently even though it never has the slightest bearing on the plot.
I've made this film sound a lot more fun than it is, but between the gunfights, of which there aren't that many, there are long dull stretches punctuated by the most stilted dialogue you've ever heard, and several subplots which promise more action than we actually get because they're left unresolved. And it doesn't help that, as with so many seventies films that nobody cares about any more, the surviving copies all seem to be horribly lo-res video to DVD transfers cropped to fit a TV screen. Possibly of interest to connoisseurs of special effects so bad they're kinda funny, or people who want to see Charles Bronson doing his best to look scared of something that wouldn't be out of place next to a bouncy castle. Otherwise, don't bother.