Yeah, it's tough to play a controlled game because you have people running around like nuts. I played a match tonight where it was 3 on 3 and the entire other team had P90's w/ double tap on it. Talk about a ridiculous amount of bullets.
The M16 is a good weapon for controlling your shots. You can be a little more mobile w/ it, but you don't just spam everything w/ bullets.
I just started using the shotgun again and forgot how much I love it. It's great for those surprise encounters, one, maybe two shots and they're done.