In retrospect, my adventures with hardcast bullets in the .458 WM are quite hilarious. Not so funny when I was experiencing them.
I started with a box of 500 of Berry's Bullets, store-bought, 405-grainers, plain base, grease-grooved, blue-lubed from the factory. They measured .459" diameter and weighed 409 grains on average including the lube. BHN 20, by my Lee test kit.
46 grains of AA-5744 made them go 1884 fps (instrumental, 5-yards) from a 24" barrel of .459" groove, 1:14" twist. They were all KEYHOLED and shooting like buckshot in cylinder bore pattern.
36 grains of AA-5744 gave 1568 fps for 5-yard velocity, half made round holes, half made keyholes, pattern tightened to full choke.
26 grains of AA-5744 made them go barely supersonic but gave three-shot, sub-MOA group at 1182 fps MV, same rifle.
I settled for 30.0 grains of AA-5744, that gave a 1.5" group for 3 shots at 100 yards, MV = 1378 fps. I especially liked that load because it had a 5-shot ES of 10 fps and st.dev. of 3 fps.
Next bullet, same rifle:
Same 30.0-grain charge of AA-5744 (no filler) worked well with a .459"/485-gr Lyman RNGC, grease-lubed. Good accuracy and uniformity. Two different 5-shot strings chronographed with my Oehler 35P at 5 yards averaged 1335 fps and 1334 fps, 72 to 75 degrees F that day at the range. So for 10 shots I called it 1334.5 fps average = 1335 fps. Add 7 fps to correct to MV: 1342 fps MV
So use 30.0 grains of AA-5744 with your .459"/ 465-grainer and you will probably get >1350 fps and <1400 fps, with hunting accuracy. That ought to BAGWELL. My COLs were all short, 3.080" with 409-grainer, 3.180" with 485-grainer. F215 primer or WLRM primer, R-P brass or Hornady or WW-Super. Use whatever you have on hand and skip the trial and error wasting of bullets.
Now I know to use .461" hardcast bullets with smokeless powders for highest velocities in the .458 Winchester Magnum with .459" groove. But a .459" bullet at sub-1400 fps is cool beans from same rifle too.
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.
