The side lever cocking is the best system, in my opinion. You simply press down on the side lever until it cocks the rifle. In this system the back trigger is the usual rifle trigger (most drillings use the front trigger), and cocking selects the trigger for rifle. Sauer and Merkel used this system a lot prior to WWII.

Another nice feature is that you can uncock it by simply holding the lever all the way down and pulling the trigger, then let the lever up slowly.

I saw that same drilling, but I think they are not sure what they have, and it is probably a 9,3X72R. That needs to be determined and in no uncertain terms. Being an older gun, it may be loose, also. If it is a 9,3X74R and still on face, it would be a fun and useful combination.

L2S