That IS the correct serial number range for the last run of 1884 Carbines (5000) made in 1889. Mine is 452770. A lot of carbines and rifles were refurbed at Rock Island Arsenal for Span-Am War militia issuance; that explains the lack of cartouche, so you have made it over a couple of the hurdles.
The lock issues(s) are another matter. I can see them perhaps using a dated plate, but you additionally go on to say "1873 lock". If you mean an early hammer, or (especially) a two-click tumbler, then I would say that something definitely IS wrong. The faking of carbines has been a cottage industry for nearly 50 years, and the perps have gotten pretty good at it. Ultimately, it gets down to what one feels is real, on a case-by-case basis. A mixture of parts will often reveal itself by finish/wear differences.
I never believed there were SO many STUPID people in this country. Start working now to take the Senate in 2014.