Reply To: A question probably only John can answer (pintle mounted MGs).

[johnlyons 5389xp 3]

On the M48 I have seen two hatch types for the commanders position. One being :

The other being this monstrosity…

The first one showing that big pintle mount, which, to my eyes, looks to be locked horizontally. I know on the older WW2 era mount that the gun cannot be locked in any other position but horizontal. And this one on the M48 would, in my opinion, be the same. As others have pointed out it keeps the gun where it’s “less likely” to catch on low hanging things and, to a degree, offers the commander some protection from traps like wire strung at head height for tank commanders between building and the like. (yes, that was a concern, and yes some vehicles had addons to protect troops form that threat, see below!)

(The long, angled peice of metal on this Ferret’s turret front was for cutting wires and obstructions before they removed the commanders ability to think)

Externally mounted guns on the cupola of a vehicle, as others have said, normally needed to be manned from outside the tank. Partly why you rarely, if ever, see a .50 cal mounted on top of british Shermans past, maybe, the desert campagin as they decided it wasn’t worth getting out of the tank to operate.
Also of note is that cupolas generally could rotate themselves

This Sherman hatch assemylu can rotate 360 degrees with that gun mount able to rotate itself. So the cupola can be rotate to have the gun mount out of the way and locked in that position. Both the gun mount itself and the cupola have independent locks to achieve this.

It makes sense to me that the M48 commanders cupola can do the same. But maybe I’m applying too much logic to something built by the DoD.. 😉