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

Here is Marcella the .458 WM+ M70 with 23" No.4 McGowen barrel shortened ftom a 26" to 23" so muzzle is barely thick enough (0.670" muzzle diameter).
Next time I will go with a a No. 5 McGowen Sporter Contour. I am not getting any younger.



The First 6 shots fired through Marcella were to see how her true .458" groove diameter and usual 1:14" twist reacted to known ammo.
It was no different than other rifles up to .459" groove diameter that I have.
Hornady 500-gr DGX ammo is supposed to be 2140 fps in a 24" barrel, we assume at 70*F.
Marcella gave 2125 fps MV.
Add 15 fps to correct for the 1" shorter barrel and she is right at 2140 fps MV at 55*F.
Hornady makes good factory ammo for the .458 WM:



The handload is a .458 WM+ standard of 400-gr GSC HV with 80.0 gr of AA-2230 +2500 fps in my 25" barrels (Shilen & CZ),
the perfect "running deer" load.
By golly ! The McGowen 23" at 2511 fps MV did about the same as the 25" barrels with .459" grooves.

After that I cleaned the barrel, then shot 50 rounds of cast bullets, the red ones I posted most recently above,
Here is what Marcella's muzzle looked like after 50 rounds of powder-coat-painted bullets and AA-2230:




Add-on weights for Marcella: