Several items come into play: rifle, type of scope, type of mount, is the scope any good. Most WW I scopes are garbage with lenses separated, replaced, chipped, parts missing, seized adjustments or a dent in the tube.
WW I scopes are a hard repair and of them are pooched, parts not available which you have to make, lenses are chipped and separated and lens to have made aas no stock lenses around.
If it is a WW I sniper and the scope is good there is also a 90% chance it has been put together as most were broken down after the big bun fight and the scopes sold to the trade for use on hunting rifles in the 20's and 30's.
Anything in a WW II sniper is rare and exotic which is the reason the humpers are putting them together. Not saying this one is but the chances are it is a put back together