bipbigbore, I load my .450 Rigby with converted Norma .416 Rigby cases and the same 550gr Woodleigh solid as Norma, at simmelar velocity (about 70ft/ sec faster), and they work very well. I also just had a client that shot with the 350gr .375 load, and except for his hippo, where he shot too low, it worked very well on his buffalo and his elephant.