I'm using a Heritage .22 revolver.
(
http://www.heritagemfg.com/traditional.shtml )
I wanted a gun I could use to fire blanks for training, but also needed a target/ small game gun. It came with the 22LR and Magnum cylinders for $129. I'm carefull to never carry live ammo when training. also I clean it often because the blanks leave a lot of carbon in it and I wouldn't want to fire a live round through all that debris.
The down side is the 22 blanks are more expensive than primers. The cheapest I've found was 5.99/100 at
www.lcsupply.com. These often jam the cylinder though. The better blanks I buy locally cost 8.99/100, and Remington power loads 4.99/25.
I like the power loads because they're louder, but $$$$.
This is not a suitable option for tests or areas which require blank-only guns, but I like it because it gives me more versatility.
Some day I would like add a primer/ blank pistol to my gear collection, maybe both.