I used to use 180 gr in a 6" S&W M27, and that was a very stiff load. I'd never put it in my Python, though. :image035:
There are also some 180-grain offerings with things like Barnes bullets, but I'd be more inclined to use those in a long-barrelled, dedicated hunting gun like a Contender. Buffalo Bore also has some 180-gr hard cast solids, but I'd still go with a 158 JSP in a medium-weight gun like the Security Six.
BTW, I have a 6-inch Security Six with Hogue grips, and with those 158 JSPs you know you're shooting a serious load!