Bullet: 500 gr TSX  (Barnes)

Diameter: 0.458"

 

Powder: Reloder 7 (Alliant Powder)

Starting Powder: 51.0 gr

Max Powder: 55.0 gr

 

Primer: FED 215m

 

Case: Winchester Western

Trim Length: 2.490"

 

Cartridge Overall Length: 3.340"

 

Starting Velocity: 1,775

Starting Pressure:  

Max Velocity: 1,921

Max Pressure:  

 

A slight crimp was used to ensure the bullet neck tension was strong enough to keep the bullet from moving
Barrel: 24" with 1:14" twist.

 

Source: https://www.barnesbullets.com/wp-content/uploads/2021/05/458WinchesterMagnum.pdf