As to the .22mag gun, I'm looking for a pistol. I have a .22mag rifle by Marlin. Nice shooter.
A .22 mag is both too large and too long to fit into a .22LR chamber.
There are some .22 revolvers which have a cylinder for each. The tiny difference in the bullets diameter does not seem to hurt accuracy too much.
In short if you have a Ruger Single Six with both cylinders, the WRF and Magnum will both work in the same cylinder. Neither will fit the .22LR cylinder.
I am not basing this on theory. I have fired lots of WRF in magnum chambers.
The Kel-Tec PMR-30 looks interesting. Thirty rounds in a single magazine that fits in the grip!