I've tuned many different AW mags, and almost always that process includes bending the internal spring a bit. One common symptom is that the rounds either don't pop up in the mag all the way into the feedlips (insufficient spring force) or that when they pop up the rear case head doesn't come all the way up at the back of the mag (incorrect spring angle).
You can add spring force by pulling the follower out of the mag (grab and twist/yank it out) and then stretching the spring. The angle issue can also be fixed by careful bending of just some of the folds in the spring. I've found that bending it so the rear of the follower is higher and parallel with the tail end of the spring has helped.
Final tip, make sure your rounds are all fully stacked equally on top of each other when you load the mag. I like to give the mag a solid whack on the palm of my hand to seat all the rounds fully backwards in the mag. If they are randomly I stacked foreward/backward that can cause issues with feeding sometimes.
