Hmm, most here are going to recommend an AK with 10,000 round drum magazines, at least 10 of 'em loaded, and of course it has to have a picante rail on it just in case one of your attackers has a bag of doritos on him.
However, not being a tacticool kinda guy, I understand. Personally, I sorta like my .45 Colt/.410 barrel for my contender for survival scenarios, not that it's anything more than a fun barrel at the range, but I mean just thinking about it. It's certainly no IMHSA barrel, though! ROFL! It shoots about 7 MOA due to excessive freebore. I haven't tried using that metric caliber rifle brass yet in it to reduce the freebore, might work as I do reload.
When I was IHMSA shooting, I bought a barrel and dies in 7mmTCU. I got to where I could run 35 out of 40 with it, not too bad for a beginner with 10" barrel and irons shooting stock class. You'll need an IHMSA micrometer click sight on it which I think TC sells. I got mine used from the guy who got me into shooting the sport. He and his wife had graduated to these spacey lookin' custom things that looked like something out of Buck Rodgers and shot like lasers, too. His wife routinely shot 40 of 40 and would outshoot him ALL the time, ROFL! Anyway, you need to think FLAT shooting and I don't know that .460 is flat enough. 7TCU was invented for the sport, but of course you must reload. You can't even buy brass in the caliber to my knowledge, had to fire form mine from .223 brass. I found commercial was the way to go. Used military brass didn't neck size with very much ease and I crunched a lot of it trying. Commercial brass is a lot more malleable when neck sizing up to 7mm.
In commercial, if you're shooting a contender and don't plan to load your own, I'd suggest a .30-30 barrel or perhaps a 7x30 waters. But, the .30-30 leverlution loads would be quite flat shooting and 7x30 is hard to find even in flat nose anymore. It never went over too well as a commercial round. You won't lack power in the .30-30 either. My .30-30 barrel has collected 5 one shot kills as far out as 90 yards on deer. It's a good, flat shooting caliber. Of course, I handload Nosler ballistic tips in mine.
Eventually, you'll want more'n one barrel if you're getting a Contender. I have a .22LR barrel, a 7mm TCU, a .30-30, and the .45/.410. I think a .223 might be fun, if useless, and I've always fancied getting a .22 hornet barrel for some odd reason. Also, a .45-70 barrel will take anything a .460 would take far as game goes. I read an article once calling it the "150 yard sledge hammer", pretty appropriate. But, it also hammers the other end of the grip. My .30-30 is a peach. I have the 12" hunter barrel with built in compensator. It doesn't come with sights, though, scope mounted barrel. The super 14 would work or a 10" will be mandated for stock class.
Guys use rounds like .454 and .460 in IHMSA. I ain't saying you can't use one, just that if you're going to shoot a single shot pistol, I think a rifle caliber is better and will get you a higher score. JMHO
BTW, why is this posted in "revolvers"?