the discussion about the use of 22 lr shotshells for shooting small game in the trap comes here regulary like christmas. anyone who try it says it don't work but people coming allways from outside and ask for this cartride when learning it exist because it seems to be the right thing. anyone trapping had a rimfire gun or pistol and looking for a cartridge that can be used safe so why not the little shotshell.
I had the rare orportunity to try a smooth bore with this cartridge against a common rimfire rifle. common concept is the shot get a spin in a rifled barrel that gives a hollow shot. the gun I had was probably a smooth bore 6 mm Flobert for the 6 mm Flobert shotshell sometimes reamed out for the 22 lr.

the old 6 mm flobert shotshell, made last time maybe in the 1980s by Fiocchi

the .22 lr rifle shotshell I use, made by RWS but other brands on the market must be similar

both targets shoot at 6 m, you see the carpenter's rule on the right side
aiming at the black dot

with a smooth bore, shots a little high

with a rifled bore

conclusion - the target with a smooth bore is noticeable better but with a rifled barrel is not so bad as you would believe. this 6 m distance is maybe the maximum you can use it but for what? with a smooth bore you can shoot mice in the kitchen but for rats it probably not hit hard enough.