Re: m118LR deadringer
The original loading of the M118 was 44gr of WC846 (occasionally W748 is recommended as closely similar) or 42gr of IMR4895 with the LC 173-175.5gr FMJBT.
The initial M118LR was the same loading with the 175SMK substituted.
The USMC had issues with lot-to-lot consistency of IMR4895, the manufacturer refused to address the issues, and Reloader 15 was pressed into service. I am not privy to the published M118LR data on the Reloader powder.
The loadings are published loadings which are, in fact, simply estimates, or plausible fictions. The arsenals do not load to a recipe, they load to a velocity. They test with the current lot of canister powder, establish a loading which achieves the targeted velocity, and this becomes the recipe for that particular lot.
IMHO, the published WC846 and IMR4198 loadings are hotter than is wise, especially in military brass, and in fact exceed published Sierra max loads, even in commercial casings. Further, the original loads had temp sensitivity issues, and this may or may not have been properly addressed in later loadings.
IMHO, while it may be desirable to duplicate a given load for purposes of matching zeros, the task is not as simple and straight forward as it may appear on the surface; and such a goal may have limited benefit when contrasted against specific load develpment for the specific rifle.
The latter strategy nearly always yields better performance.
Greg