>>64105523
>I’m making an FPS set in the late 1890’s. Basically you are a vampire hunter and you have to kill vampires and shit. Like castlevania meets doom.
MARANAX INFIRMUX

Assuming it's 1899 and that you're sticking with stuff that actually made it off of the drawing board but ignoring practical availability, I would say that the best you could get would be the following and I'll put anachronistic options in brackets and mention the best calibers when it seems relevant. The latest gun on this list is the MG 08 from 1908, I think.

Self-loading handgun - Mauser C96, Luger [Colt M1905 in .45 ACP]
Revolver - Colt New Service in .45 LC, Webley Mk. IV, Colt SAA in .45 LC, S&W No. 3 [Webley-Fosbury]
Shotgun - Winchester M1897, Winchester M1887 [Browning Auto-5, Winchester M1901 in 10ga]
Single-shot and double barreled rifles - Farquharson rifle, Winchester M1885, Sharps-Borchardt, single and double barreled hunting rifles [in NE chamberings]
Levergun - Winchester M1895 [in .405 Win.], Winchester M1886, Savage 99
Bolt-action rifle - Lee-Enfield Mk. 1*, Mauser Gew 98 in 8x57 [CLLE/SMLE, Sringfield, Kar 98 magnum sporting M98s]
Self-loading rifle - Cei-Rigotti [Remington Model 8/FN 1900 in .35 Rem., Chauchat]
Machine gun - M1895 in 7x57 [.30-06], Maxim Gun, Hotchkiss machine gun [MG 08]