A semi-automatic gun like the MTZ Interceptor is one of the main options in Modern Warfare 3, and marksman rifles are the most popular. As long as you have the loadout to support it, marksman rifles like the MTZ can kill enemies in a single headshot even with the increased time to kill for MW3.
The best attachments for the MTZ Interceptor in MW3
In addition to being fairly slow by default, the MTZ also kicks pretty hard on every shot. Because of that, I use four attachments, and a fifth optional slot with greater ADS speed is even available. We still need to control that kick without making the weapon move like a bag of rocks every time we aim in.