MP7 - needs slightly lower accuracy and lower damage.
Type 97 - needs to be more like the Famas from MW2. It can't have higher accuracy AND higher firerate AND higher damage than the M16, because then the M16 is obsolete. They need to bring down the Type 97's power to M4A1 levels.
ACR - slighly lower accuracy. It's just a little too accurate, though if nothing is ever done to this gun it would be OK, IMO.
AA12 - needs a buff to damage, bigtime. Infact, all shotguns need a damage buff. Shotguns should completely outclass EVERYTHING in close range combat. That's the point. If anyone is within a three foot radius it should be an insta-kill, even if only one pellet hits the enemy. I'm sick of clipping a guy in the abdomen, then have him spin around and spray me to death. However shotguns can't hit anything beyond thirty feet. That's the trade-off. Shotguns completely outclass everything in close-quarters, but are completely outclassed everywhere else.
Close - Shotguns
Medium/Close - SMGs
Medium - Assault Rifles (they are like the Jack-of-All-Trades)
Far/Medium - LMGs
Far - Snipers
C4 - I believe that C4 should be made more tactical. First, cut the throw distance to around 1/4 it's original length. (Those who like to throw it around corners and blow it up will have to settle for grenades. It's terrible, I know). Second, double the explosive radius. Even if it's not doubled, at least increase it. I think that C4 should function as a means to kill people in high traffic areas, or to kill players who storm a building in order to secure a flag or something like that, and at its current power it is just not a very feasible option. It should be a means to secure areas for your team (hold down roads, guard points, etc.). Place it in smart locations and it is deadly. For those people who enjoy throwing it, that's what grenades are for. Third, give players two C4 per life so that way they can put one on the left side of a street and the second on the right side. This will make it far more effective. Fourth, and this is the point I'm still unsure of, do not have C4 disappear after death. Instead, have the player spawn with the ability to blow the charge after they respawn. Only once the charge is blown and the player respawns will they get the option of placing more C4. Enemies will have to watch out.
While I can see problems with this, I also think that it will be great fun. That way a player can sneak behind enemy lines and place it on a minigun, and even if they die it will still be there. Then wait for an enemy to begin shooting that minigun, and click - BOOM. I think this will be fun, however the idea of being blown up at your spawn is not a fun one. That is why you must cut the throw distance down to 1/4, so it is much harder to place in locations. This will require players to actually be where they want to place it, and can't just throw it over a wall. At the very least, please consider my first three suggestions.
Jammer - increase jamming range. At it's current size it is very useless. I suggest doubling the range, and maybe have it affect Pointstreaks, as it affected the RC Car in Black Ops.
I hope you consider what I have written. Thank you for your time.