Its one of the retro looking C-15s, and Im pretty sure the thing is as old as I am. I am literally stripping the lower receiver bare and starting fresh with the weapon. I am attempting to take the things I dont like about the Stag M-4's we have in my unit and overhaul my personal rifle with durability and versatility in mind, with a few trinkets in mind. I also want to keep it at a medium weight, as carrying it will not be any sort of issue (I used to be a 240 gunner). The weapon will eventually get used as the ultimate ranch rifle for back home. This is a list of what I have already ordered (from bravo company usa):

DPMS lower parts kit (semi)
BCM bolt carrier group (MPI) - Auto
BCM Milspec Receiver Extension (Buffer Tube) 6 Position
BCM Standard 16" M4 Upper Receiver Group w/ Centurion C4 7" Carbine Handguard
BCMGUNFIGHTER Charging Handle (5.56mm/.223) w/ Mod 4 (MEDIUM) Latch
Carbine Action Spring
DPMS Armorer AR15 Wrench
EOTech 512
H2 Carbine Buffer
Magpul MBUS Gen 2 REAR Back Up Iron Sight - BLACK
Receiver End Plate
Receiver Extension Nut (Castle Nut)
Yankee Hill Machine Phantom - Original 4 Port

Other parts I have:
MS3 sling (I have a clamp on adapter that clamps to the buffer tube I have used on my M-4 for a year now that works completely fine, so I will not be buying a special end plate)
ACS Stock – Mil-Spec Model
MIAD Grip Kit – AR15/M16
MOE Trigger Guard, Polymer – AR15/M16

What I am still debating on:

EOTech G33 STS (3X Magnifier w/ Switch To Side Mount)  
Geissele AR15 High Speed NM Service Rifle Two Stage Trigger
LaRue Tactical EOTech QD Mount LT110

Is the magnifier really worth the purchase? In my experience its not terribly difficult to hit a 300m target with a COMPM4 sight, let alone an EOTech without the aid of a magnifier. The NM trigger is something I have always dreamed of having in my service weapon, 7 lb trigger pull is a little ridiculous to me if you practice good weapons safety and positive identification. But is the trigger truely worth the investment? And lastly, the QD mount acts as a riser for both EOTech optics, and apparently is supposed to align then better than a standard picatinny rail does, as well as make it more comfortable to fire. Thanks guys.

I would take that $$$ and buy another rifle.

so you are replacing everything but the stripped lower? just buy another stripped lower, build the gun out how you want, and keep your DPMS or sell it