Which gun gives the most damage in a short amount of time on battlefield 3

The Saiga 12 G, the FAMAS, and the SCAR-H seem to be the best weapons when it comes to killing quickly and efficiently. The Saiga 12 G is a semi-auto shotgun, and with the right ammo type and a quick finger you can own the battlefield. The FAMAS is known for its fast fire rate and accuracy, maybe even better than the Saiga, but doe not have the best iron sights. That can be fixed once you have earned a red dot or acog scope. I have not got a chance to try out the SCAR-H yet, but from the reviews I have read it seems that it may even be better that both of the the previously mentioned guns.