It was called a 38 Single Action, 2nd Model revolver and all made of this model fired 38 S&W ammunition. Remington and Winchester have recently manufactured this short round, but have not looked for any recently since I load my own ammo. They were manufactured from 1877 to 1891 so all are antiques. Your revolver's serial number appears to be 66377 and it would have shipped around 1881 or 1882. I have shot mine in the past at cowboy events as a pocket revolver and it functioned just as new 120+ years later.