If you look close you can see the ammo is really blanks in the pic above.
After semi annual unit qualification there was always a ton of ammo to shoot up once completed (either that or bury it). I laugh because no one wanted to shoot their weapon more that the forty rounds because they'd have to clean it. Since I was in the motor pool and had to drive the truck, draw the ammo, ferry the unit to and from the range, and had access to tools and solvents that did a bang up job with clean-up I assumed it was my duty to empty every piece of brass issued. I fell in love with the M60 during those afternoons, the feel, the sound, the smell, wish I would have bought one when I had then chance. Man I love those guns, shoulda, wouulda, coulda...