I think Wes' pic is of a German MG 15 in 7.92 x 57. It was a aircraft defensive armament, in more than just the waist position, In fact, I don't think the Germans had much in the way of waist positions on other than on the He 111. Also, I think it could be twin mounted and as such was called the MG 81.
Also, I'm still curious about MG 34's pic.
Steve