Good Job! and welcome aboard.
For a first time venture, you did very good. I have almost the same set-up, except they were out of the 24" barrel at the time, so I went with the 20".
Like JD pointed out, there are a few
type things though. Now, take it as just my own personal opinions, you built your piece the way you saw fit.
1) I probably would have elected to go with a different forearm on there, instead of the 4-rail. But, that all depends on what you want to be able to do with it, and what it's main purpose will be. If you are building it for long range shooting (hence the Magpul PRS, 24" 1:8 twist barrel, palm-swell grip, scope), then is the 4-rail necessary? I guess if you are planning to add some type of lighting/infrared/etc. you would want it. But you could probably shave some weight off by going to something like the YHM smooth rifle forearm:
or maybe the JP Enterprises V-Tac
You can add rails to either of these, for mounting whatever you want to mount, and they weigh less than most 4-rail forearms.
2) Again, like JD said, loose the vertical fore grip, unless you think it looks like you want it to. There really is no need for one on a gun like this. Instead, invest in a good bi-pod, a Harris, Versa-Pod, etc.
3) Get some better glass for it. You don't need Swarovski or Schmidt&Bender, or that price tag. Go to Natchez or SWFA or Optics Planet, and check out the selections. You can get a very good Leupold/Nikon/Burris?etc. for under $300. Leepers is ok, mainly made for air soft and paintball type applications. I'm sure some will say different, but you can find better without breaking the bank.
4) Break the barrel in, per DPMS's instructions, cleaning after each of the first few shots, then after the next 5, or whatever it was. Again, some will say different, but on two similar barrels, I went with their instructions on one, and just started shooting the other w/o the cleaning. There is a noticeable difference - not much, but easily seen on the targets.
5) Lastly, after breaking in the barrel, shoot it, pay attention to your breathing, sighting, trigger work, and shoot for groups. After a couple hundred rounds, you should be able to tell if you want a trigger upgrade or not. Here, your options are many. Ranging from less than $100 for a good trigger job, to $100 and up for 2-stage NM or single stage triggers (Rock River Arms, Armalite, DPMS, Bushmaster all have NM 2-stage triggers) or you can buy a Timney, Chip McCormick, Geiselle, ATC Gold, Wilson TTU, etc.
all in all, you did very good and should be proud of your work. Looks great. Let us know how it does.