.
FWIW, the earliest recorded production date for a Model 1894 is Oct 20, 1894.
The first change of consequence to the Model 1894 receivers was the very early change of the cartridge guide screws, then a change to "Extra Steel", then a "Nickel Steel" alloy,etc, etc, etc to the final change to "Proof Steel" in 1933-34.
As noted, the M1894/94 changes tend to be tied to SN range's, rather than to a specific date - since the changed parts were usually tossed into the same parts bin as the older-style parts (no parts were ever thrown away, just because there was a change) - to be used whenever they were pulled from the bin for use in assembly.
.