Your brother doesn't have a Stevens Pocket Rifle (it's a smoothbore) - he has a Stevens No.42 Pocket Shotgun, most likely chambered for the special .44 Everlasting shells (the .44-40 was an option, since it was available in a shot loading before the .410 came along).
They were available as either a 15" bbl ($11) or an 18" bbl ($12) model at the time.
The Everlasting cartridges were just a heavy walled cartridge that could be reloaded almost indifiently.
Almost any Ballard or Stevens rifle could be ordered chambered for Everlasting cases, but, in most cases could also fire normal factory thin walled cartridges.
The .44/50 and .44/65 Stevens Everlasting cartridges were the shot shells primarily used in the Stevens New Model Pocket Shot Gun and in the Stevens Hunters Pet Shot Gun. (Both of these models were smooth bored.)
I wouldn't recommend he (or anyone) fire any .410 ammo in it, by any means.
Last edited by PetahW; May 2, 2013 at 04:50 PM.