Ha, been there, JimKirk. Yes, MRP indeed is what im after. Whats an example of the powders you mentioned that are of different labels?
USSR, RL-22 is what i currently have for the reason you mentioned. These will be the first loads i have done for this gun and caliber (300 Wby.) On a Weatherby forum i joined, the MRP powder is the only way to go for that caliber in the opinion of many but they also recgonize the RL-22 as being nearly identical. I have four test groups of RL-22 loaded and ready to go right now but i had always intended on getting my hands on MRP to compare the two since i was under the impression it worked the best. I know i should just probably test what i have first. Honestly i will admit that if i find the velocity to be as advertised in the manuals that i took data from and if one group is sub moa then there is no reason to keep looking.
I reload for about 50% enjoyment/hobby and %50 increased performance and really none for cost because im not a high volume shooter but that said, i can purchase RL-22 locally and with no other choice but to order Norma (i did find it in stock at powder valley), i realized its about $25 extra for hazmat shipping and that just seems like a waste of money.
Thanks for your comments, guys.