I have a DPMS LR 038 with 24" bull. My gunsmith installed a Timney trigger and checked the crown. Nothing to do to the bolt, really. After break in we get .75 MOA at 100 meters with Black Hills 175 gr match.
I just received (after 6 month wait) a complete lightweight 18" barrel upper and got it broken in over the weekend. Other than operator error fliers, 40+ of the break in rounds (not Black Hills, of course) made a ragged 2.75" group 2" low. I tried to make good trigger pulls, but otherwise wasn't taking much time with sight pic or thinking about adjusting the scope.
I was working on hunting loads for .30-06 and .300 WM, so haven't done anything for the DMPS yet. I'll look hard at the loads on the DPMS LR-308 thread.
Get the "piece of crap". I've been happy with my DPMS AP4. It's not a match grade gun, but I don't believe it was ever meant to be either. It has served me well and put venison in the freezer and a smile on my face banging steel. No, I didn't pay $2500+ for it either. If I could I would, but my growing family doesn't allow me the luxury of owning the "best". If you can afford the LaRue or the LMT, then I personally would spend my money that way.
I'd go with the DPMS and take the money you saved and invest in a new trigger and put the rest towards a higher quality scope.