Revolvers, no problem. Shotguns, no problem. However, regarding a rifle, I strongly recommend that unless you plan to use .357 cases for all and forever, you spend a little extra time looking for a marked .38Spl. rifle, like my Navy Arms 1866 replica, instead of a .357 that will take .38s. This presumably rules out Marlins, but I've seen way more jams in Marlins than I have in Ubertis. It will save you headaches later, especially if you get into serious competition where you can't afford to have a hiccup.
I moved on to .45LC because I found the cost of reloading not that much different and the bullets were closest to the original .44-40s without the hassle and expense of the thin-wall .40-40 cases.
Note that some spotters listen for the "blang" on the steel instead of watching for the splash in the dirt behind it, relative to a miss. If I see spotters like that, I grab my box of 250gr. loads (versus the usual 200gr.) and there ain't no doubt about the "blang" when those suckers hit.
Best bet is to shoot first in the stage if you can, since the paint is still on the steels and you can prove your hits. But if you are a newbie, that ain't gonna happen anytime soon. All that said, CAS is the most sporting, good-time, good-sportsmanship discipline in which I've ever shot. If your gun breaks, many of your competitors will loan you theirs. You can't beat that with a stick. Best sport I ever got into, even though I'm getting a bit too broke down to participate much.