I'm shooting 300 grn Lapua Scenars usuing 92.5grns of Retumbo, .050 off the lands.
Start lower-maybe 91.0 grns, move up in .3 grain increments. I would find a good group maybe starting .030 off, then play with seating depth to see if the groups improve!
Sounds like one heck of a bullet to try out! Let us know your results!
Dennis
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