Home Forums Hunting & Shooting Express Rifles and Big Bores Only The great 458 Winchester. Everyone should own one at least once

Sir Darryl,
Good on you for getting that Garmin Xero.
It will help immensely in getting you up to speed on your handloads, sort of a pun intended.
I have not even had a chance to use mine yet, looking forward to the luxury.
Count your blessings that you have a Brother nearby to share Mom.
My three ne'er-do-well siblings do long-distance "love" only.

Q1: Do not fear limited case capacity even with 3.34" COL.
Until you say what bullet and powder you want to use, I could flap about forever.
AA-5744, H4198, Benchmark, AA-2230, AA-2460, H4895, and any powder good in the .223/5.56 Nato: Lots and lots of powder lots,
just about any lot you got.
Those are just a few of my favorites.
I could do it all with H4895 from 60% of max SAAMI loads to +110% of max loads,
if willing to load to pressures and lengths within the limits allowed for the .458 Lott.
Make of brass too must be specified.
Norma is over 4 grains H2O bigger and Peterson is about 1 grain smaller than all the following makes:
Federal, Remington, Winchester, Hornady are all about the same, in the 94-95 grains H2O range.
Also, do not think you are limited to 3.34" COL in your 3.425" inside length of magazine.
Crimping locations that work well with the 404-gr Shock Hammer are 3.28", 3.38", 3.48", even 3.58" at the extreme.
I like my CEB 400-gr FN loads at 3.36" COL.
Your rifle will eject loaded, unfired rounds up to 3.54" COL, bullet tip clears to eject in the standard M77.
Loads up to 3.395" COL work like a charm through your magazine repeater.

Q2: The 404-gr Shock Hammer and 400-gr CEB brass FN may use the same powder charge,
but it all depends on factors mentioned in Q1.

One possible load combo with 78.0 grains of Benchmark:
GM215M (same as F215) primer
Norma brass case
24-1/4" barrel
1. 404-gr Shock Hammer at 3.380" COL: 2463 fps MV (starting load)
2. 400-gr CEB Brass FN at 3.360" COL: 2506 fps MV (one and only load tried 5 holes in one at 50 yards)
Differing charges and COLs:
3. 404-gr Shock Hammer at 3.580 COL with 84.0 grains of Benchmark: 2612 fps MV (Max load)
Also 5 holes in one at 50 yards and only 1/2" above the CEB load, very near same POI.
Close enough for pairing at 100 yards too, but when one bullet has a G1 BC 0f less than 0.2
and the other one is greater than 0.4,
think dead-on at 100 yards with the FN and then 2 to 3 inches high with the pointy one.

Q3 & Q4: The 250-gr Monoflex at 2700 fps with either AA-5744 (not your usual reduced load) or H4198 is practical. +3000 fps not necessary but possible.
A really fun load that duplicates the old BP 45-70 pretty closely and is good for banging gongs out to 600 yards:
The old Lyman "Government" bullet, plain base, cast in Linotype and sized to .461" and powder-coat-painted as only lube,
it weighs 487 grains like that.
Load it to 3.375" COL with 36.0 grains of AA-5744 and NO FILLER.
24-7/8" CZ take-off barrel on a Pre-'64 M70,
Oehler P35, 5-shot standard deviation = 3 fps, 1436 fps MV.

Pick up your load manual for the .458 Winchester Magnum and start low and work up, in your rifle.
Let that Garmin Xero be your guide.
72.0 to 80.0 grains of AA-2230 is the short-COL SAAMI-satisfying charge range for the Barnes Original 400-grain cup&core SSSP.

Many here at the Square Table will be able to address any specific load suggestions for a given bullet, powder and brass combo.
Soon you will too.

And hey, a pocket plate for the Ruger M77 has gone from Big Lake, AK to Anchorage, headed for KY, and I don't mean KY Jelly.
Might be a good addition to your WunderRifle too, to turn it from a 4-shooter into a 5-shooter.