To Tim Armitage and olli.....thanks for the great pictures. Some very unique markings there.
These are surely some very early MG34s from back when they had time to thoroughly stamp every part.
All the cosmoline reminds me of the scene in "Sergeant York" where the guy from Brooklyn is getting his rifle (an M1903? a 1917?) inspected by the armorer before turning it in. The armorer asks, "What's with all the grease in the barrel?"
His classic answer...."It makes the bullets come out faster!"
Please keep the pictures coming...Phil