bullet sponge or bullet stopper

What is bullet sponge or bullet stopper?

bullet sponge or bullet stopper meaning in Military or Military Slang terminology / glossary / dictionary is:
(U.S.) An infantryman, MOS 11B “Eleven Bulletstopper” most commonly the point man of an infantry fire team who is usually the first member of the team to engage, or be engaged by, the enemy.

 

reference: Glossary of military slang