(You need to Login to view media files and links)Have been going off of this guide, but this thing doesn't seem to conform to any single one of them, The 1899 carbine can in fact have an 1898 receiver, but it should have an overstrike on the "8" with a "9'". On the other hand the front band is wrong for a 1898 rifle, as is the rear sight I think.
To add a further wrinkle:
(You need to Login to view media files and links)M1898 CARBINE 5000 MANUFACTURED
M1898 CONVERTED CARBINE 3000 MANUFACTURED
M1906//1899 CONVERTED CARBINE, PHILIPPINE CONSTABULARY 5002 MANUFACTURED
M1899 CARBINE FIRST MODEL, 1896 9000 MANUFACTURED
M1899 CARBINE SECOND MODEL, 1898 16000 MANUFACTURED
M1899 CARBINE THIRD MODEL, 1901 2000 MANUFACTURED
I am genuinely stumped. I got the gun almost 20 years ago and I'm not entirely sure what it is. The closest guess I have is that it is an 1898 rifle converted to an 1899 carbine.