How to Quickscope in mw2 ps3?

You use 1 sensitivity??? Personally i use 9-10 sensitivity. You should get used to using higher sensitivity with any gun first. then get out the intervention, put slight of hand pro ,stopping power(doesnt really matter but if no stopping power you could just get a hit marker) , and steady aim(doesnt have to be pro) . You have to have quick reflexes, you run out and u see a enemy quickly move towards him and aim not all the way and shoot(a perfect quickscope would be if the enemy is right in the middle of crossheirs but you dont have much time to perfectly aim) you just know the perfect time to shoot