There is an issue with melee in general, and perhaps with Juggernaut in particular, I don't know. Facing and targeting seem very slow versus ranged classes, and I'm calling anything over 4m ranged.
Maybe it's just my system (or your friends) but half the time you think you are hitting a target they aren't where the client says they are and you aren't doing any damage. The other half of the time you get a "you are not facing the target message" when you are looking at right where the client says the target is.
They are supposedly working on fixes for this problem, which affects different people to varying degrees.
Until then I shelved my juggernaut and rolled an operative. That way the up close lag won't affect me as badly.
Maybe your friend has the same problem, maybe he doesn't.