The way some hilariously overpowered guns are completely ignored by the Call of Duty community. Take the DP28 for example. ITS A THREE HIT KILL AT ANY RANGE WITHOUT STOPPING POWER. Or the L86. 40 damage with a 750 RPM? Thats 30000 damage per minute - you only have 100 health in multiplayer. You could get a killsteak-less nuke with one round drum of ammo, silenced without stopping power if all bullets hit. Whats are your views on this?
EDIT: I like the way Treyarch added minor things to guns that gave them a huge advantage/ disadvantage/balance
E.g. the mp40 has the lowest range of the smgs, the highest recoil, and does 29 minimum damage. This makes it crap in hardcore :)