Sounds like a horribly modified body buster...
Instead of the medicine ball we have the instructee hold a rifle at chest level with their elbows held tight to their sides. From a bottom squat the instructee rolls backwards, elbows touching the ground before their upper back, shoulders, and back of head touch. Continuing to roll backwards the instructee pulls their feet, legs, and lower torsos over themselves and their rifle (which now should be held against their chest). The instructeeâ??s toes (front of boots) should touch just above their head before rolling back up, explosively, into a bottom squat (the instructee may use their rifle in any manner as leverage to get themselves back up). Immediately from the bottom squat the instructee performs a quick leg thrust and performs one push-up (yes, while still holding the rifle) and then knee thrusts back into the bottom squat. Repeat for many, and I mean manyâ?¦
Body busters are typically executed in the sand and/or other friendly surface for obvious reasons and many times performed in full gear, helmets and all!
This is an advanced combat readiness exercise (ACT-Advanced Combat Training) and never performed by an instructee unless he or she can perform full bottom-to-bottom body weight squats correctly with their backs relatively straight, chins up, and heels on the deck. Correct form can be taught in a week or two, under military conditions, via wall squats, duck walks, walking lunges, and plenty of body weight air squats.
I have heard this exercise (without a rifle of course) referred to as a body blaster or body breaker.