Was at a Cabelas last week and saw some Norma MRP on the shelf. I have not seen any MRP in 10 years, maybe 15... I bought 2 lbs just on impulse. Now I cannot find any loading data...
I have a old 300 Wea. I thought I would try some in.
Never thought I would see this product again. I think it said on the side of the container that it is distributerd by Western Powders. It is in the same type of container as AA powders.

EZ

If all else fails you can get by with RL22 data.

Many call them the same powder. Depending on the lot of RL22 it is sometimes a gr or 2 hotter than MRP.

I have some RL22 that loads gr for gr with my old MRP loads.

Norma MRP is very good stuff. It's been on sale from Powder Valley and Midway for quite some time. It was a replacement for N205. Thus, N205 data may be a good approximation, in addition to the R22 data suggested by Paul.

Normas load data.

http://www.norma.cc/en/Ammunit...00-Weatherby-Magnum/

I have an old Hornady 3rd edition that shows a bunch of MRP data for the 300 Wby. 75-85 grs for a 165 gn SP, 72-81 grs for a 180 gn SP. One needs to use caution with that dated info though.

I believe Waters pet loads has MRP loads for some cartridges.