That 358009, is that the 280 grain bullet?
I've read several people have not had success with that in the Remington Whelens due to the 1:16" rifling pitch. I wonder if it couldn't be driven at closer to full-house loads an if you could get better accuracy.
After some time playing with cast bullets, I've become a bit skeptical about the velocity limitations often bantered about. Indeed, if you push a cast bullet too hard it will strip. But I don't think it's as simple as assigning a muzzle velocity as the limiting factor.
There are other factors that seem to play in. Bearing surface seems to be one, in my experience. Acceleration force is another. Shooting a heavy-for-caliber bullet maximizes the bearing surface. So a heavy 280 grain bullet should be able to tolerate a bit more force than a short 180 grain bullet.
Also, so often the cast bullet loads seem to use fast powders, even pistol powders. In theory, you should be able to get a cast bullet up to 3000 fps with no problems IF you have a slow acceleration and IF you have a long enough barrel to do it in. My Adams & Benet barrel with a 1:14" twist will stabilize a 280 grain bullet at 2250 fps, probably even slower (that's actually the slowest I've shot it at). I'm shooting a paper patched bullet. One powder I use to get this is RL-19 which is slow for a Whelen.
