This does in no way take anything away from your rifle, but it is interesting
MY GUN HAS AN 1883 (or 1884) DATED LOCKPLATE . . .
This feature indicates that you do NOT have a rifle produced at Springfield, though some of its parts were made there. Thousands of surplus parts from early 1873s were once sold as scrap. But, when SA discovered that the buyers were making up entire guns and selling them, the disposal program was summarily halted. Receivers were sometimes in bad shape. Some SA barrels were available, but others, often having five(5) grooves, were obtained from various commercial sources - and some were even made (contracted for) new, by the large firms such as Bannerman. Lockplates were always scarce (SA reused them on the starred arms) so they often had to be fabricated by the arms merchants. Other common "wrong" features of these "fraudulent" (as they were termed at the time) arms are odd rear sights, strange ramrods, total absence of a ramrod keeper, reworked musket stock with lined barrel channel, etc.