When Grizz shot at Bravo, multiple rapid fire shots occurred even though he was only carrying a single shot bolt action rifle.
Nobody takes away someone's horse like Grizz did to Willow at the beginning of the movie, when she fell off her horse. That is horse theft and would result in serious criminal prosecution. Grizz was never prosecuted for the act.
Nobody would come onto another rancher's property with a gun to shoot a horse because it hurt their son, as Grizz did. That would be criminal threatening and prosecutable under the law. Grizz was never prosecuted for the act.
Nobody would deliberately aim at and try to shoot a horse with a girl riding it, as Grizz did. That would become attempted murder as killing the horse could also result in killing the girl if the horse fell on her. Grizz was never prosecuted for the act.