About the smallest .22s that I can recall,in "recent years",that Colt made,were the derringers that .22 rimfire recalled from the '60's. They were single shot,side swing,in .22 short,I think. Sold mostly as "commemoratives",I think they were called "Lord & Lady".Not "toys" or replicas,but fully functioning guns.
Last "small" or "mousegun" .22 I can recall,are the 3" .22 Cobras,made up to the early 70's. I have one,ANIB,and while not a powerhouse,it will "do" in a tight spot,using "Stinger"hollow points and eye and nose placement.
Bud /forums/images/graemlins/laugh.gif