Sounds like lag or deliberately going for limb shots. The average lifespan between someone in the CQ maps doesn't deviate much between HC or not. Chances are if two people turn the corner into each other, neither will manage to run down their ammo completely by the time someone dies.
Ofc CQ isn't as bad, it's easy to consistently hit someone in the range the CQ maps have, even on full automatic, but medium to long range on B2K maps for example is straight up terrible even without the silencer.
The game was running at 100+ fps, with a 30ms ping and it has client side hit detection so it most definitely wasn't lag.