if they work, .22 powernailgun blanks might be the best choice, as they are cheap and way easier to get. They are also crimped rather than having a paper wad out front, so there is nothing to get stuck in the flash hole.
I took some of the hotter ones (#4) out back one night in a .22 ruger revolver and fired them. I saw flame. I don't have any regular .22 blanks to compare them to, so I have no idea if they are good or bad.
This was talked about here briefly last year, but no one ever reported back as to actually trying them.
Preacher, if you are set up to use them, wanna try them and let us all know ? Most hardware stores seem to carry them (Ace usually, Home Depot and Lowes for sure).