The Army is still buying M118LR with a charge of Reloader15. It currently exists side by side in the inventory with M118LR Mk316 which has the IMR4064 charge and Fed GMM primer.
Currently the Army is looking at a PIP (Product Improvement Package) for M118LR and the Navy (Mk316 was developed by NSWC Crane for SOCOM) is shaking their heads and asking "why?"
They exist with the same DODIC in the inventory and are being issued side by side in theater (regular units get M118LR, SOCOM units get Mk316).
They are ballistically identical at 70 degrees F, but Mk316 shows less variation with temperature extremes than the older version. The Leupold Mk4 scope has a BDC turret that is calibrated for M118 under "standard atmospherics" so removing temperature from the equation lets snipers in Afghanistan focus solely on elevation as the major factor in ballistic change.
I don't know why Re15 is considered less temp stable than IMR4064, as it is advertised as a temp stable powder, but the math I was taught for MOA shift was 1 MOA difference per 20 degrees with M118LR and 1 MOA for every thousand feet above sea level, IIRC.
Machine guns are awesome until you have to carry one.