Enaa baasee' Sir Bob, The lore of the .458 Winchester Magnum is duly annotated with latest Federal Factory Premium Safari Trophy Bonded bear Claw 400-gr MV in 24" barrel (Ruger No. 1) at 45*F: MV = 2282 fps.
The Federal Factory ammo with old version TBBC 400-grainer was also advertised at 2250 fps MV but in my 24" barrel (M70 Winchester) at 77*F 8-shot instrumental average = 2333fps, MV = 2345 fps for BC = 0.353. Standard deviation for those eight shots = 23.9 fps. As usual, we know we can do better with handloads.
At least the new TBCC seems to be a better bullet than the old one, and they are getting closer to hitting the advertised velocity, exceeding it by a lesser amount, not bad, heh-heh-heh. Probably can't get them as component bullets (?) for hotting up to .458 WM+.
Ron aka "Rip" for Riflecrank Internationale Permanente NRA Life Benefactor and Beneficiary .458 Winchester Magnum, Magnanimous in Victory THE WALKING DEAD does so remind me of Democrap voters. Donkeypox.