Looking for magazine advice on a long action 300WSM

[JAYgs8163]

Any reason you couldn't use a 300wm and add throat for this bullet?
With a Wyatt's box extension, you can go to nearly 4".

The "Bore rider" bullet is a special designed bullet and doesn't require additional throat.

 

[Frogman77]

For the last 3 years I have been running 250gr Atips out of my 300 wsm with 338 lapua magazines. Mag lips need to be adjusted a little but it has fed awesome.

 

[MT-JONAS]

For the last 3 years I have been running 250gr Atips out of my 300 wsm with 338 lapua magazines. Mag lips need to be adjusted a little but it has fed awesome.

Do you care to share details and pictures? I'd welcome a DM if so…

 

[Earnhardt]

For the last 3 years I have been running 250gr Atips out of my 300 wsm with 338 lapua magazines. Mag lips need to be adjusted a little but it has fed awesome.

Velocity?
Barrel twist?
Freebore?
Thanks