My 24" Encore loves the cheapest of everything:
WW 243 brass necked up
CCI #34 primer
surplus IMR 7383 powder
PMC 139gr PSP
groups like this:
[Linked Image]

My DPMS LR 260 doesn't like anything so far. I have tried AA4350, IMR 4230, IMR 7383 and IMR 4064. Also, 140gr Sierra's, 139gr PMC's 129gr Hornady's and 120gr Rem's and Noslers.
Best I could get so far is 1.25" @ 100yds. I'll try H4350 and 130's next.

Some is Good---More is Better----Too Much is Just Right