A while back I had a 375 Rimless Nitro Express (375 RNE) built. My rifle is built on a (BSA Monarch) Herter's U9. It has a 25" barrel. I make my cases from 30-06 brass.
I have been developing loads for primarily jacketed bullet. But my intent is to use cast boolits. I contacted Accurate Molds and we designed the 37-270M bullet. While I have had this molds for more than a year I finally got around to casting some boolits.
My goal was to work up a load using this bullet that would match factory ammo. Sometime I get lucky and on my first attempt I got pretty close.
While I was working up loads for jackets bullets I found that 42 grs of Rel 10X with a 270 gr FBSP clock-in at 2203 fps. So I used the same load with my paper patched boolit and it came in at 2229 fps. So far my group sizes are matching those for the jacketed loads I have used;1 to 1 1/2 Inch groups a 100 yards. I think it would produce smaller groups if I my scope had fine crosshairs instead of crosshair and a post.
Please remember this loads is safe in my rifle and it isn't published in any reloading manuals I could find. In fact, I could only find reloading data in The Cartridge of the World book. Nothing for cast boolits.
I have recently purchase a 375, 270 gr boolit mold from NOE but I have not used it yet.
A lot of people have provided me with data and I found some in a Mannlicher Schoenauer Collectors Association Newsletter.
I love Wildcat Cartridges and old oddballs like the 375 RNE. They are a lot of fun.
CA Dude