Will a Helmet Stop a Grenade?

No, but in the opinion of other infantry veterans, Dunham did the right thing. Anyone who covers a grenade with their kevlar is going to be severely wounded. ... But his helmet likely absorbed all of the grenade's shrapnel and allowed his fellow Marines to come out relatively unscathed.

Can you stop a grenade by jumping on it?

One of the squad throws their body over the grenade and makes a Heroic Sacrifice. The Mythbusters examined this in 2007 and confirmed the myth; jumping on a grenade will significantly reduce the injuries to those around, but it's still a very good idea to get clear.

Can a military helmet stop a bullet?

So the answer is an absolute YES! Bulletproof helmets are meant to protect the wearer against different combat-based threats such as fragments, gunshots, shrapnel, explosions, etc. However, a gunshot is not always from normal range during combat.