Nice rifle! I also own a Nowotny double in 8x57jr, though a later manufacture. Mine is toplever hammer. My rear sight is also marked for 2 ranges, and I find a fine sight with the bead down in the notch is correct for the close range, and a coarse sight with the bead even with the top of rear sight is correct for the longer range. I am aware that some older 450 ex. chambers are too tight for modern cases, but have found that also in British rifles, just assumed the old Kynoch brass was thinner, as it will usually chamber fine.

Enjoy- you certainly have a finely crafted rifle there!

Doug