I suspect every soldier or marine remembers nthe "infiltration course"...
It looks by this video that it has changed greatly. I went through the basic training twice,.. 1955 and 1962.
In the old "brown boot" Army (1955) the machine guns swept across the field at 36 inches..enough to get a ricochet off the old M1, if some trooper
somehow got his rifle vertical.
Tracers in this video, look like the bullets are clearing the field at 5-6 feet.. Remember; one tracer out of every 5 rounds fired.
By 1962, the guns were stationary, and at 42 inches...however, both had quarter pound charges of TNT in pits, spread across the field...which
would blow up whenever any troop got near them. ..Don't see them in this video..
https://www.youtube.com/watch?v=TVbWzrlZOS8