You are shooting sub-moa.That is pretty good.
Now,realize,from the perfect center of the target,there is a sum total of less than 1/2 moa to find gains.What?
A hound dog can only run 1/2 way into the woods,after that,he is running out.Radius versus diameter.You have the radius to work with.
That 1/2 moa is divided up.
Some is still shooter error.
Some is the barrel.I'm not knocking your DPMS,but I would not have the same expectations from it that I would have from a top line barrel from a custom barrel maker
Some is likely copper fouling,correctable with Bore -tec eliminator and a nylon brush.Use a good one piece rod and a bore guide.Not doing damage is important
Some is in the ammo.Your rifle may prefer a different bullet weight,or ogive or seating depth.You may get better results with a different powder or primer.
Some gains can be had from a basic brass prep,
Trimming squares the neck and makes them the same length.
Chamfer helps keep the bullet from being damaged in seating
Light deburr of the flash hole.Keeps the primer flamefrom being distorted.
Brush out the necks with a nylon bore brush,Clean is good,makes a more uniform bullet release.
BTW,I took those steps from Precision Shootings Guide to Reloading for High Power competition,the steps to make "pretty good" ammo.
They also describe using an O-ring under the die lock ring or more concentric ammo.
OK,now,remember,to a degree,each of these steps may give you some results in reducing that less than 1/2 moa radius ,that is how far each individual shot varied from center.
You may pick up 1/16 in here,1/8 in there,etc,but that is where you are.
You can do as much of that as you like,
But some might say a next step would be getting that "How to shoot" book from CMP that Mr kraigwy recomends,and a shooting sling,and working with prone,sitting,etc.
Oh,you get extra bonus points for the wind!!Good job!You made improvement