Just my two cents. I would go with a S&W revolver, not your cheapest option, but by far the simplest option. Smith makes a few very nice revolvers, no bells and whistles, they are fool-proof to shoot. No safety, no slide release, no magazine, no magazine release, just fill the cylinder, aim, pull the trigger.
Is there much of a difference between the Ruger 22/45 & Mark III?