I think like most shooting events, except for the Palma Match where the host country NORMALLY provides the rifles and ammunition and the competitors must use those, the Olympics leave the choice of firearm and ammunition to the competitor, or his team leaders. Of course, I am sure there are specifications that must be followed, such as caliber, or range of calibers, depending on events, perhaps barrel length limitiations, overall weights, sighting equipment allowed, etc. These rules change as technology changes firearms. I recall shooting for my High School Team in 50 ft. indoor smallbore, the limitations on the rifles then (no hook buttplates, certain sight radius, no palm rests, three-pound trigger pull, etc.) would have caused every rifle used anywhere today in the same events to be disqualified.