I'm using HRBC .459 405gn projectiles, but I use the "Copper" series which are supposed to tolerate higher velocities. I load up 99gn of AR2209 in my .45-120 giving 2350fps. This is a larger case than the 458wm, so don't try my loads of course. These bullets make nice round holes in the paper targets. I did try some "silver" 350gn from HRBC and they sometimes ended up sideways. Try the "Copper" ones. I use fed215. Also, my .45-120 has a very short "throat", it won't take 500gn Woodleigh for example, so I'm probably close to the lands with these bullets. I'm sure your 458wm is very different in this respect.