Highly suspicious...
The 303 came up in 1889 and was not even cordite...
Ballistite first came in 1889 before Cordite existed.
Mk I Cordite showed up in 1892.
The likely round would have been the 450/400 3 1/4' and I think that the first one was about 1898 IIRC.
I'd say there is a mistake somewhere.

1896 maybe, but 1886 I think not...
Later date reproofs were fairly common, and that's another option.
WC-