Im not familiar with WC 846 powder but I have used IMR 4895 although 44.gr seems pretty hot for a 172 gr bthpI have not tried to replicate that load yet, I did find a load for the M118 but it doesnt refrence the "LR"
I was planning on trying to do a load work up on this in the near future.
here is a screenshot of an army load data manual # TM 43-0001-27 it does have some very interesting info and I highly reccomend it if you havent taken a look
...I did find a load for the M118 but it doesn't reference the "LR"