This is more of a personal request, but I think the same calibers should do the same damage, or at least they should be very close to each other. For example I understand that a sniper rifle's 7.62x51 should deal a bit more damage, than a shorter barrel SCAR-H CQC, but still, the SCAR should be a lot more lethal, than 5.56x45 for example.
The SCAR-H dealing as much damage as the M4 and the M16 makes no sense at all, since it has a 20 round mag capacity vs the standard 30 round and they both handle the same. (all of them are controllable)
Same goes for the MP7. As of this moment it just doesn't deal enough damage. It's a 3-4 shot to kill weapon, while in reality the ammo it uses is compared to rifle rounds, not SMG.
Also another thing I noticed is that the .50 BMG doesn't tear human parts apart. For example, when you shoot someone in the leg with a .50 it should immediately detach. We're not terminators made of adamantium.