I am not sure this ammunition is just for training, but it could well be. We called what is being described the “Infiltration Course.” We had to crawl about 100 years on a course perhaps 100 yards wide, and it included crawling under barbed wire entanglements, past sand-bagged pits (to keep you from crawling in) where they exploded C-4 or Dynamite blocks, I don’t know which, electornically to simulate burts from morter or artillery rounds, all the time shooting live ammunition over your heads.
Everytime I did this course, the guns were old M1917 water-cooled MGs, picked I’m sure because of their long-burst capabilities. The ammunition was linked as normally, with every 5th round a tracer. Towards the end of the course, if by that time you were dumb enough to be crawling right under the line of fire of one of the guns, and stood up, you could be killed. The course at Ford Ord had a slight uphill grade to it, and for most of the course, despite what they told us, I think the line of fire was probably over a tall man’s head. There were only four or five guns on line, so that put one every 20 or 25 yards, so actually, very few of the troops were actually directly under the line of fire… They were NOT traversed during firing. In fact, even though locked in the tripods, the barrel casing sat in a wood frame so that the barrel could not be dipped or swung from side to side by accident.
Part way up the night course, I got directly under the gun and when I turned over on my back to crawl under some wire (in the rain, of course, and almost submerged in a puddle), it was pretty exciting. The tracers seemed like they were about two inches above my nose. Of course, they were probably six feet over me, or perhaps more. After going thru the wire, I made sure I wasn’t under the gun anymore, though.
I think they used specially selected ammunition. I never heard anything about worries over defective, disintegrating bullets - not that it means a thing since the grunts never get that kind of information - but we did hear there was “good ammo” to insure no underload dropped a bullet’s trajectory down to hit anyone.
Seemed dangerous to us at the time, until we started thinking that some day we might have to do it where they were trying to hit us. I am not sorry that never happened for me.