djc, Your S&W American is a US military gun and a factory letter will only say that it was shipped to Springfield Arsenal, per US Gov't contract for 1,000 guns in 1871. These guns were issued to the 2nd thru 7th US cavalry regiments, and your gun was one of them. The x4 is the assembly number and you will find it stamped on the barrel between the "ears" and maybe on the bottom of the barrel latch. If you look closely , you will find small letters "A" and "P" stamped in the cylinder flutes, "A" being for the Gov't inspector, O.W.Ainsworth, who inspected the gun. His cartouch was on the grip also, but has probably worn off by now. The "P" is for "proof", indicating the gun has passed the cartridge proof firing. The grips have been switched at some time in the past, however the grip serial number is also a US gun, so the switch probably occured during the period both guns were in service. Springfield Research Service,a private organization, can tell you if they have any record of the gun's assigment to a soldier and/or which cavalry unit. They have copied the Military records in the Archives, and will research your gun for a small fee. .44 magnums, .44 Special & .44 Russian cartridges will not fit in your gun, only .44S&W American cartridges. Some of these US Americans were at the Battle of the Little Big Horn, I have one in my collection that was recovered from the Indians in Canada after the battle. Some of the fired cartridge cases excavated from the battle site in the 1980s are S&W American cases. The "oil hole" guns stopped at about serial number 1500. The "Oil HOle" is a collectors name for the small hole in the bottom of the barrel assembly. It has nothing to do with oil, but was an air pressure release for pressure built up in the extractor mechanism when the action was opened to eject spent rounds. At least that's what factory engineers thought, however it turned out that it didn't make that much difference in actual use of the gun. Actually US American Model w/o the Oil Hole are scarcer than the Oil Hole variation, but most collectors look for an Oil Hole example. Value of your gun is somewhere between $5000 and $8000, depending on overall condition and how much original finish might be seen, if any. Ed.
