I've done a number of Ruger rimfire conversions. I've done them by lowering the block as well as moving the firing pin location. If you want the finished gun to look like a standard Ruger, we can start with anything that is .30 caliber or less. I do the conversion on the action and then sleeve the chamber and reline the barrel. I've had good reports of accuracy and done this way it isn't too expensive.
If you would like to talk about it give me a call at work. Johnson's Sporting Goods 517-265-2545.
Steven Durren