Re: AR-10 build
Since you have a DPMS lower there are a couple key things to consider, and like Lonewolf pointed out, it's not an AR10.
The DPMS pattern will take PMAGs. I'm a big fan of these and have 6 so far for my Mega. They run about 18-19 a pop but check your local Kali laws. Midwest PX has done mods to the mags to make them so they don't hold as many rounds. (I live in WY so mag capacity doesn't affect me at all.)
A LPK from DPMS or Fulton plus pistol grip and buttstock will get your lower completed. I got a Fulton kit minus trigger for less then $60 and used a Giessele in my Mega. If you're going lightweight, and budget, then use an A2 stock. If you're going collapsible you will definitely want to get a CAR10 buffer and spring which unfortunately runs $110 or so. So it all depends on whether you want collapsible or fixed and whether or not the Peoples Republic of Kalifornia allows it.
For upper receivers you could buy a factory upper or build one. Building one allows you to have the parts you want, buying one means its a done deal, your choice. However if you do build you will need to verify your reciever height if you get a DMPS A3 flattop. They decided to change their rail height for some reason so there are now 3 heights; their tall slick side upper, and 2 A3 heights. The older height allowed for better aftermarket matching of rails. The new height you have to use their rails or you can get a Troy since they offer two heights. Or you can skip the DPMS height BS and order a Fulton, they have a slick side that will cut down on weight.
For lightweight I would suggest a tube with the ability to mount short accessory rails. Quad rails on a hunting rifle will weight you down. Having the short top rail will allow for a BUIS and short bottom for bipod. Fulton and JP make DPMS pattern tubes with ability to mout rails.
Rainier barrels are a pretty good price, you should check them out. I bought their Select bbl in 18 inches and used a Vltor gas block. Since you have DPMS pattern the gas tube lengths are the same as AR15s. You could get their Ultramatch barrel if you have the money to spend. They were out when I built mine 3 months ago but the Select is a great buy for the price.
So here's a break down of what I suggest.
Lower-
Fulton LPK minus trigger
A2 stock with DPMS spring and buffer
Pistol Grip of your choice
PMAGs
Upper-
Fulton flattop slick side
Tube of your choice
Rainier bbl of your choice
GB and tube
OPS Inc buzzle brake
DPMS BCG
There is a quick list of what I would build if I was biulding a lightweight hunting rig. My Mega is a beast and weighs in at the 14-15lbs range and is a pig to hump but I did it Elk hunting. Other then the Mega receiver mine is all DPMS pattern.
PM me if you have questions.