Bullet: 270 gr Spitzer BTSP  (Speer)

Diameter: 0.375"

 

Powder: IMR 4451 (Improved Military Rifle)

Starting Powder: 76.6 gr

Max Powder: 85.1 gr

 

Primer: CCI 250 Mag

 

Case: HDY

Trim Length: 2.570"

 

Cartridge Overall Length: 3.320"

 

Starting Velocity: 2,616

Starting Pressure:  

Max Velocity: 2,879

Max Pressure:  

 

Compressed
The 270-grain boat tail bullet is slightly longer than the 285-grainGrand Slam. If a charge fills the case, the BT doesn't leave much room and we did not apply as much compression with the BT as with the flat-base bullets. That's why you'll see some compressed charges for the boat tail are lighter than those for the heavier bullet.

 

Source: https://reloadingdata.speer.com/Downloads/speer/ReloadingPdfs/375-ruger-with-270-gr-spitzer-btsppdf.pdf