IIRC, this is a cast bullet forum. Can't believe how many members use jacketed bullets for hunting. Haven't loaded a jacketed round in over twenty-five years. I take most of my deer with archery tackle. Next would be muzzle loaders using RB. Occasionally, one with a carbine or pistol with cast.
I don't have a 450BM, but a 45 caliber cast bullet is going to make a significant hole, very reliably, whether at ten yards or two hundred, st 1800 fps or 900 fps. I'm surprised I don't read more about people loading these with cast. Why else shoot a 45 other than to take advantage of the large diameter? Copper jackets and plastic tips sell ammo though.
Not picking on anyone's choice of caliber/cartridge. Just thinking in terms of going BIGGER specifically to get away from the need for extra speed needed to make expanding bullets of smaller bores do the job.