Ruger single actions with 2 cylinders come in 22lr/22 wmr, 45 Colt/45 acp, 357 mag/9mm, 10mm/40 s&w. think they even made on in 44 mag/44-40. would love to see one in 327 Federal Mag/ 32-20.
I have the 9mm /.357 one (not for sale because it is a 9mm {see sig line}) I'm intrigued by the 10mm one.
They also did a 10mm/.38-40. They were done for a distributor in Ohio called Buckeye Sports. I distinctly remember them because there was a buckeye/buckeye leaf logo stamped on the top strap. They also did one for Buckeye Sports in .32 H&R Magnum/.32-20. Both of these guns are commonly referred to as Buckeye Specials.