Absolutely what nico said.
A free float tube has the capability of literally shrinking your groups in half - across all ammo types. Even if not a 50% reduction, it will still be significant.
The AR is a very accurate platform due to the lock up and gas system. However, you can turn a 1.5-2moa rifle into a .75-1.25moa rifle just by free floating that barrel. A FF tube is the #1 accuracy enhancing AR modification by far.
You've got the nice trigger, so you're set there. There's really nothing else you need other than a free float job to get good accuracy. You could take a look at better optics, or ergonomics. Better grip and stock can make YOU shoot better. You could get a match crown cut on that barrel if a gunsmith thinks it will be an improvement over what you currently have.
Aside from all of this, match-ammo is your friend. A quality match-grade ammunition will allow you to get the best out of your rifle. Don't expect excellent accuracy from any standard ball ammo or from military loads.