No. MG3 (modern version in .308). Mexican military bought 10,000+ of them in 2002.
Interesting collection. Looks like someone's private stash of WW2 war trophys. Guns that old should have long since been on the BATF list.
If I recall correctly, 8mm is shorthand for the 7.92 German round, and I wonder if those 280 7.62 rounds are 7.62X54R. You have to wonder who there were stolen from, or, if when Granddad died, Grandma called the sweet young guy from down the street, the one with all the friends in his yard every night, and asked if he wanted them...