Not a .458 but I did shoot a moose last October with my .450-400 3" Nitro Express and Hornady factory load 400 grain DGX bonded. Range about 80 yd. Bullet expanded just fine despite only 2050 FPS muzzle velocity. 1st shot broadside thru the lungs and exited, good size hole and damage to vitals. Second shot was not necessary and not placed well ( it was getting dark) but shot the moose again as it turned to leave, entered right ham, broke femur, went thru entire body and was found under the skin of the opposite shoulder, expanded nicely and still retaining almost all of its weight. Didn't mess up much meat either. I'd use Hornady DGX bonded bullets again for moose or bear. Suspect they'll do fine in your .458.