World War 2 RAF veteran air gunner with Browning machine gun

This photo, of a World War 2 RAF veteran air gunner holding a Browning machine gun similar to the kind of gun he would have used during WW2 is pretty puzzling

It’s his expression that is puzzling; has picking up the gun reminded him of being in combat? It’s tempting to claim so, but it’s too plausible an explanation, it’s too easy to explain it in this way.
There is no physical connection between his picking up the Browning and his using a Browning in action. No World War 2 air gunner ever picked up a Browning machine gun, they were fixed to the ‘plane.
Ok, in that case was just handling the gun responsible for his expression? Possibly. It could be that the shape of the gun – the cold, lightly oiled steel, or the aura around it – its potential to cause death and destruction, revived his memories of World War 2.
The truth is, probably no-one, apart from the few surviving World War 2 RAF, USAF and Luftwaffe air gunners, can speculate with any accuracy about his thoughts.

World War 2 RAF veteran with Browning machine gun