The MTAR is a standard assault rifle with no special characteristics that you unlock as your first assault rifle. It feels a little underpowered (in terms of damage) but other than that is is very solid. It is suited for an passive aggressive game strategy that involves using cover aggressively.
At the end of this guide there is a YouTube video with a visual version of this guide.
The MTAR does not have good hip fire characteristics so any class around it has to be built with that in mind. Unlike the MP7 (click for a weapon guide for that gun) you move very slowly when you are aimed down the sights which means that you can’t strafe to avoid enemy fire. Thus you have to use cover to gain an edge over your opponents. But don’t sit behind some cover for the entire game, when you can’t see opponents from some cover move on towards where you think more enemies are. Be sure to keep pushing objectives as they are rewarded greatly when completed.
The class I recommend you use looks as follows:
Since you are going to be stationary for a good amount of time Flack Jacket will help you survive any enemy explosives coming your way. Since you have to aim down the sights to effectively use the MTAR in Black Ops 2 Toughness is a great perk since it reduces flinch when being shot. Tactical Mask helps you for a similar reason as Flack Jacket since it reduces the effect of most tactical grenades.
I recommend you go with a Frag Grenade, although Semtex is an almost equally good choice. The tactical grenades are up to you, but I recommend using either concussion or flash grenades. A pistol is a good secondary when the MTAR runs dry and you have to finish off an enemy.
The MTAR does not have very clear iron sights so I suggest you use an optical attachment. Which one depends on your preferences, but I would recommend you use a close quarter scope like the Reflex (Red Dot) Sight or the EDTech Sight (Holographic Sight) since you shouldn’t be at long range with the MTAR. The Grip helps you with the recoil the MTAR does posses and makes it that much easier to shoot enemies.