I used a Kelbly Atlas single shot for one of my 22BR's. With the coned bolt and the optional 'Panda' spacer, you can put any barrel chambered/fitted for a Panda on it w/o the 'smith needing to have the action in hand. That's a huge plus down the road when you want to change barrels or get another one to make it a true switch barrel setup.
Mine is in a Kelbly's Varmint stock with a Sendero barrel contour. I also have a 6BR on a 700 in a McMillan Sako Varmint pattern stock...love it.
A few pics of my 22BR Atlas...you can see the 'Panda' spacer if you look closely.
Let me know if you need more info on the Atlas, etc.
Good shootin'
-Al