It may well be used as a loop for a sling so the rifle can be used as a "Nachsuchwaffe" which is a rifle used by in many European countries for following up on wounded game. These rifles are normally short barreled and have a sling eye at the very front so that when the rifle is carried slung across the dog handlers back the muzzle does not protrude unduly outwards and therefore minimises the rifle catching on brush as they folllow up on wounded game.

Just a thought.

Matt.