That's a pretty high serial. As stated, I can prove they go into the 482K range and that's it.

Your rifle is right in the middle of the GPs. Gallery Practice. Krags converted to .22 rifles. The GPs are interspersed within the top of the Kragicon serial range, nothing odd about that, with your's being right at the top. There is a GP 150 in serial above your gun.

1898s are rifles. Carbines with the same basic guts are marked 1899.

Cheers.