I never knew that Mossberg ever built anything short/handy until I spotted a photo in the 1976 first issue of "Pistol and Revolver Digest" (sometimes aka 'PARD').
Mossberg Brownie Four Shot .22" Long Rifle.
- Mind you - I didn't know that they had made a Martini action rifle in the past either..(M11?)
Mossbergs built this wee gun from 1919 to 1932 with a double action and a rotating firing pin. - An early version was made by the Shattuck Company under licence to Mossberg when he worked there.
A very similar Model 422 was sold by Advantage Arms from 1985-1987.
Advantage Arms 422 Available in .22" Long Rifle & .22 Magnum.
There is(was?) also a 'Cop 357'
COP .357 (also Built by American Derringer Co. in 1990).