One way to find out if it is working. Go to a private match find a spot on a wall and that has markings on it. Unload a magazine into it. Then leave the game come back into the same map without the attachment and shot the same spot and check and see how much it helps or not.
Certain guns have more recoil, if it kicks up too much then don't hold the trigger, just burst fire. Also if your aim in general is abit too wild try lowing the sensitivity. Good aim usually comes with experience, don't switch guns too much as they all feel different.
If you will turn off the ingame controller vibration it can help out. I leave it on for everygame but when playing MP i dont want my controller shaking everywhere if someone is shooting back at me.
Works for me anyways.
Use Custom Games and play against the Bots to really get the feel for weapons. Definitely has helped me out.
I don't claim to be the most accurate, in fact my accuracy means little to me as you miss 100% of the shots you don't take.
But I have improved over the years. A lot has to do with learning maps. Know where to aim in certain situations. Where will the enemy be coming from? You'd be surprised how often pre-aiming and pre-visualizing will garner you kills.
Experiment with different setups, see what works best for you.