Loading 300W + H110 (vihtavuori) + PPU 145 grFMJ BT

[jope]

I have just finished my custom made 10" whisper pistol barrel. I have made it of Lothar Walther .30-8 stainless steel barrel blank.

I have the following loading components at home.

- 300 Whisper brass
- CCI 400 small rifle primers
- H 110 Vihtavuori gun powder
- PPU 30 145 gr/ 9,4 g FMJ BT projectiles

Could you help me to find a suitable recipe for making some rounds to shoot the gun in, and for later use, if the recipe is different? I have planned to make a set of 250 ( all my brass) rounds with the same recipe to get the gun and the brass shot in.

What would be the loaded length?

Anything else I should take care of?

Greetings and thank you!
- Jope