I thought the TDs BFGs were the Lewis, MG-15 & MG-34. If I remember right, the MG-42 was a heavy machine gun from WW2. Looked like a bulked up version of the MG-34 but I could be wrong.
EDIT: I found some links to compare the 2 guns:
MG-34- http://world.guns.ru/machine/mg32-e.htm
MG-42- http://world.guns.ru/machine/mg33-e.htm
They're pretty similar, but I don't recall ever seeing the MG-42. I may have missed it though.