I use 16.2 grns of Lil Gun with 158 grain XTP HP and Remington 158 grain SJHP in my Marlin 1894 carbine. I get 1864 fps and 1891 fps respectively, and these are well below max saami loads. Single digit sd and es from these loads. These "should" be ok your 1873 which is proofed to saami specs, but the toggle action is inherently a weak action so double check to make sure.

Regards,
Manny