I don't understand that very early serial number you have. I have a best grade .500 3" falling block Alex Henry rifle that has a 24** serial number and was made (or finished) in 1872. I also had a .577 3" double rifle and a 20 bore double rifle with serial numbers consecutive by Alex Henry in the 36** range and they were engraved on the barrels "November 1874" and the name of the Maharaja of Patialla. I would guess your rifle is much earlier than 1875 based on those serial numbers. Could it have been a Patent number instead? Patent numbers were the consecutive number of actions based on a certain patent number. My falling block has a patent number engraved on the top of the action. Hope this helps.