FFL's: what are your thoughts on universal SSE kits?

[FNH5-7]

Hey guys,

What are your thoughts on "universal" singleshot exemption kits? Do you feel comfortable doing transactions using these?

Its a 22 caliber barrel that slips into the barrel of a larger caliber gun. Haven't seen any pics but I've heard that some guys are using these.

[asm_]

Can it actually shoot 22 caliber with the conversion kit in place? If not, I'll probably steer clear of it.