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

Sir Scotty,
I started to do that to my standard SAAMI .458 WinMag M70 but since it is a later South Carolina/FN-Winchester,
my Connecticut Classic mag box is a different fit.
The mail-order parts at Midwest Gun Works out of Missouri are for the M70 Classic, not the SC/FN M70.
I would have to rob another SC/FN .375 H&H rifle to make the switch.
There are all sorts of possibilities ...

I will illustrate the SC/FN mag boxes and followers for .30-06, .338 WM, .375 H&H, and .458 WM ... to be continued.
I am most comfortable with recommending a switcheroo on the Connecticut Classic M70,
having done that myself, a .270 WCF 3.4" to .400 Whelen 3.6"
which was as slick as your conversions to long box .300 WM and .338 WM.

But I take heart in this:

My SC/FN .458 WinMag has an inside box length of at least 3.410"
which easily handles my 3.380" COL with 404-gr Shock Hammer,
and 450-gr CEB Safari Solid at same 3.380" COL.

The unaltered rifle will also eject a single-loaded, unfired round with COL of 3.540".
Easily ejects 3.480" COL with the 404-gr Shock Hammer.
No change in ejector/boltstop required.
No milling on the receiver required.
No magazine box switcheroo required.

Having a +3.6" mag box is desirable but not necessary.
The factory +3.4" box will handle a magazine feed of 3.380" ammo, no problemo.

Loaded with WW/Hornady brass the 450-gr CEB/3.380" gives +2350 fps in a 24" barrel.
Loaded with Norma brass, the 404-gr Shock Hammer at 3.380" COL gives + 2500 fps,
equivalent to the preferred 3.480" load of 404-gr SH in the WW/Hornady brass.

The 404-gr Shock Hammer may be loaded to 3.480" COL with Norma brass,
and that will be better than trying to load it to 3.580" in WW/Hornady brass.
Not enough bullet remains in case for 3.580" COL with the 404-gr Shock Hammer.