UMP with kick is just as beast as it was in MW2, actually I feel that it's a much better gun overall in this game. The main gun issue for me is how bad they made the M16 and AK-47, which were two of my favorite guns in MW2. The M16 is still viable, but you can only use it effectively on certain maps like Village and Interchange, and the AK-47 sucks basically unless you go kick/silencer. Shotguns are a waste of time unless you want to claw and scrap your way to the higher levels to get range and damage and watch your K/D sink as you do so, though the benefits of range/dmg on the USAS and KSG are worth it. You're still much better off going with an SMG or anything else over a shotgun, they should have left them as a secondary weapon.
