The guns were normally sold with a bullet mould made to match the caliber of the gun, so the balls fit without patches. Patches were not used in pistols of that era, and military pistols like the M1842 did not use them.
FWIW, here is a Deringer whose caliber is known, .32.
http://thefiringline.com/forums/atta...2&d=1206932555
Jim