Well, I'll make the Totally Twisted suggestion...a Star Megastar 45.
Shoots .45-acp or .45-Super without changing anything.
Progressive springs make switching ammo rather easy.
12 rd mags or 10-rd California mags available.
Downside...no longer in production, Star went out of Biz...
but if you can work your way around a Browning Hi Power,
ain't nothing on a Star ya can't fix
I use S&W 4506 .45-SUPER recoil springs for replacements.
Guy on the Spanish Pistols board makes replacement FP's,
get 3-4 and you're good for 50 years +
It is a BEAST, only thing bigger is a DEAGLE, but that makes it
rather soft to shoot, weight soaks recoil so nicely it feels like a 9mm!
Of course, you better be a big ole SOB like me to wield it