In core I've direct impacted people with frag grenades and had it immediately explode afterwards with no kill whatsoever (no blast shields involved).
I can't count how many times I've gotten hit markers from frag grenades in HC...
I vote a BIG NO. I can't count how many times I've been killed by the miracle nad chucked randomly across the map. This would just make it worse. People die a lot in MW3 because of all the twisty maps. So it's already a constant rain of nads and flashes. On the smaller maps people just spawn, chuck all their nades and stuns randomly, then run off and die immediately. Then repeat. Blast shield does next to nothing for explosions, and literally nothing against flash.
I liked explosives for one reason in MW2, to root campers out of their hidey holes. But with the way this game plays, powerful explosives would be the death of the game.
the same thing happens to me wit grenades and its happening to me with c4 and the guys im getting hitmarkers on arent even using blast shield...the only time im gettin kills if theyre hurt or if its directly under them