Cars are definitely late 30's, pic could be immediate post war. No new cars showing up post-war 'til 46-47.
Tube looks like a tube rear sight. Simply an aperture mounted in the rear opening of the tube- no optics. Used to combat mirage off of a hot barrel, IIRC. Al Freeland sold them through the '70's. Unertl made one that used standard Unertl bases and mounts. Pretty rare now.
The guy in the suspenders looks like Walter M. Cline, early (if not the first?) president of the National Muzzleloading Rifle Association, and the guy for whom the home range of the NMLRA in Friendship, Indiana is named. (Going by illustrations in Sharpe's Complete Guide to Handloading)