My 375 Weatherby achieves, with a 24” barrel, 3006fps with 260gr Accubonds, 3088fps with 260gr Partitions, 2904fps with 270gr Woodleigh PP’s and 2832fps with Woodleigh 300gr PP’s.
The 260gr load was hard on one brand of brass, so I throttled it back to just over 2900fps recently, it still kills stuff dead, so no major issues with dropping it down a touch.
Are you running R17 for those numbers ??
My house load is a 250 SGK over H-414 for 3060 in a 26" barrel. I have a little wiggle room on charge weight. But not sure how much. I know when you get 250's - 260's running that fast, a few more fps is really splitting hairs...…..but ain't that what reloaders live to do ??
