I have a .350 Rigby Rimless Magnum on a Dakota 76 action. A good friend of mine built his .350 Rigby on an FN mauser. Using modern powders & a moderate increase in pressure
( approximately 10 o/o ) we were able to improve performance dramatically. I have taken 18 animals from pronghorn antelope to eland using a 250 gr bullet at 2600 fps. Terminal performance on medium to large game is dramatic.