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

I proposed to load the .458 WM to COL 3.340" or even 3.350" with the 400-gr CEB #13 FN:

Got the 400-gr #13 early today and just finished Old Lady Duties.
Then ran to local emporium to buy ammo boxes to house the precious gems.
The ones for .45 LC work nicely.

A .458 B&M 2.240″ case made by Quality Cartridge or from RUM brass has same capacity as Hornady or W-W or R-P .458 WM brass at 2.500″.
They are all about 95.0 grains gross H2O when once-fired and not-resized, at those lengths respectively.
It’s almost like somebody planned it that way !
Use the Norma brass at 2.500″ and the .458 WM is a few grains bigger than the .458 B&M 2.240″ (Qual Cart or RUM).
Maybe Norma-based .458 B&M brings that back to parity ?
Case capacity should be considered to be identical if BLM (Brass Loaded Matters) parity is practiced.
Any internal ballistic differences between the two carts will be due to more efficient case shape of .458 B&M
versus longer throat of the .458 WM.
I think we could home-cook loads to favor either one of them, HEH HEH.

My .458 B&M with a .458 WM throat can handle 3.340″ COL
and is exactly identical to a .458 WM with 3.600″ COL for net case capacity,
with a long enough bullet to do that.
That is 1.100″ nose projection for both, not coincidentally !
Both will beat a SAAMI .458 Lott at 3.600″ COL.

I will get dummied up shortly to see if equivalent case capacity loads can be made
for the .458 B&M and .458 WM using the 400-gr #13 and the existing bands.
Knowing the COLs used for the .458 B&M pressure data would help in comparing it to the .458 WM.
Just eye-balling, it looks like 0.650″ and 0.750″ projection are possible with one band and two bands ahead of the case mouth.
.458 B&M COLs: 2.890″ and 2.990″
.458 WM COLs: 3.150″ and 3.250″

That is perfect for net case capacity match, if both are loaded with same seating depth, not coincidentally.
COL has to be 0.260″ longer with the .458 WM for it to equal the .458 B&M case capacity.
If brass is trimmed to 2.230″ and 2.490″ respectively, max COLs become 2.980″ and 3.240″ respectively.

If the third band is seated hard up against the case mouth, 0.850″ of nose projection might be possible.
I am still eye-balling this.
Then the respective COLs with the “trimmed-to” brass become: 3.080″ and 3.340″
I am going to try it,
to give the .458 WM its full SAAMI due.
Don’t laugh. I had a 360-gr./.500-cal., tipped Raptor put 3 shots into 0.3 MOA at 300 yards, once upon a time,
with only one band inside the case mouth and a boat tail hanging below that !
In the .458 WM I am going to have the base band down in case with a taper crimp above it,
running into the bottom of the third band for a hard stop.
The bullet pull may be weak but the bullet stop will be strong.
I doubt I will have to paper-patch between the base band and third band for a tighter grip.
This ain’t no double rifle ammo, so the bullets won’t get pulled when riding in a magazine.
Alignment and concentricity should not be an issue either,
with a Lee Factory Crimp.

The spectacular 400-gr #13 has a length of only 1.224″ on a sample of one I just picked out of the bulk bag.
Seating depth is only 0.374″ if bullet projection is 0.850″ ahead of case mouth.
The minor diameter of the bullet currently being coon-fingered (0.449″) is right on 0.001″ less than bore diameter (0.450″).
The band diameter is right on groove diameter minimum of 0.458″.
Keeping the optimized 3 + 1 band structure, there is hardly any other way to build this bullet.
It is totally optimized.
I will never look this gift horse in the mouth.