Single Action? Double Action? Hammerless?
All of these have the patent dates you show, plus other dates. (All dates on the barrel would be helpful.)
The serial number could also be from any of the above.
Need a little more info to nail it down, or, at least, a picture or two.
OK!!
It's a .38 Double Action Second Model made from 1880-1884 in a serial range of about 4,001-119,000.
With the serial given, I would estimate first or second year production. The only sure way to know would be a factory letter.
It looks to be in pretty good shape. If it's tight and everything works he didn't pay too much at $125.
Thanks deadin, I'll let him know. He is going to use it as part of his costume for Cowboy Action Shooting. I have already advised him not to actually shoot it with anything but black powder loads.