Another thing is that COD's controller sensitivity is very low by default.... even lower than previous games or they just use a different scare. I turned mine up a few notches.. that might help you a bit if you haven't already. I have similar stick sensitivity for BF3.. I think I run on 6 on COD and 8 on BF. I can't do the super high sensitivities like a lot of those "pro players", but I check corners while ADS quite a bit, so I need the faster motion in that aspect.
I forgot to mention If you have anything less than a full green connection, avoid the FAL! Its a monster, but any hint of lag will screw you so bad vs. any SMG. Its like that for the SWAT-556 too. Any semi auto-fire tends to be at a huge disadvantage with a mediocre connection. Surprisingly I'm rarely ever in the yellow in this game. The R870 is a different story. One of my kills on that video is a full blown lag kill at around 45 seconds. The dude was clearly to the left of me running the opposite direction when I fired off a shot and he still died. If we would have had a good host, I would have missed and who knows what would have happened.... its whoever turns around the quickest. lol
I usually use the FAL on Slums, Raid, Yemen, Meltdown and sometimes Hijacked. When people get to camp happy on the upper levels of Hijacked, I break out the LMG with FMJs and shoot the walls up. Slums is the perfect map because everyone camps in that freaking room next to the circular courtyard. I'll toss a betty on one side of the vehicle that is sitting on an alleyway and prone on the other side of it for a bit because someone is always going to pop their head out of the opening.