Used to have one. 1" x 18" tube filled with spiral diffusers over a turned down barrel. Looked just like a stock bull barrel. Worked just fine, but these days the ATF is just too much hassle to deal with.
If you want solids for small game like rats, use the CCI Stinger. It uses a light weight hollow point at very high (for a rimfire) velocity for very rapid expansion.
So9
Coolbeans.
Will give it a shot.
Won't deal with the ATF or temp their kind loving ministrations..