R-P brass holds way less powder than Weatherby brass. I have a 1-9 twist Lilja for 160-grainers. Tried 150-grain Ballistic Tips and Retumbo (--> 78 grains), which shot okay.
AA4350 and Ramshot MAGNUM shot like crap. The barrel/gun likes 162-grain ELD-X's with H 4831SC and 160-grain Federal TBT's with MAGNUM (close to factory load but 200 fps slower.)
Those are long like Barnes TTSX's and I'd try R22. Give them a long jump to the lands.

Last edited by agazain; 04/18/20.