Years ago, I started using the old Weatherby Guide's load data that included a "factory equivalent load". All calibers listed used either H-4831 (I assume the old canister type) and MRP. When i discovered MRP and RL-22 were the "same", I proceeded to test all my Weatherby calibers, 340, 300, 7mm, 257 and 240 with both powders. loads, etc. There was NO difference outside what one expects regarding extreme spread, std deviation, etc. I have however, since switched to N-165 in the 340 (VV powders btw, are the CLEANEST BURNING I've ever experienced and also RL-23 in my 300 (same load) with same results.
