Juggernaut was designed so that you survive take one more shot from any weapon. Stopping Power was designed so that you would need to make one less hit with any firearm to score a kill. The game code literally cancels out the damage effects when Stopping Power or Sonic Boom hits a Juggernaut. No increase, no decrease. The damage perks are perfectly balanced against each other. If you use "a whole magazine" to kill one guy, it isn't because of Juggernaut.YOU SUCK AT THE GAME.