I would agree with James (welcome, James!). While researching my as yet unpublished novel about Rasputin I visited the museum of the British Army Small Arms School Corps and handled a baby Browning and its ammunition. It does, indeed, fit comfortably into the palm of a hand and the rounds are tiny (just slightly larger than .22), and .22 rifle cartridges carry much more propellant, so are more powerful. You would have to be very lucky to do much damage with one! At the time of the 20 July 1944 plot, at least one German General (I need to look up which one) shot himself in the head with something similar, and lived (as did Unity Mitford, though she was brain-damaged). The standard Nagant revolver used by the Russian Army is a vastly more substantial weapon, and the .455 Webley used by the British then is larger still (and its ammunition is virtually 'dum-dum' in its effect, i.e. it mushrooms.
Ann