I pick out a bullet diameter or caliber first, such as maybe a 25 caliber for deer or perhaps a 338 something or other for Elk, Black Bear etc... Then I pick out a good Controlled round feed, fixed ejector action that I want to use to house the round. Lastly, I pick the cartridge that will fit and feed through my action of choice with the largest case and case capacity I can get in that caliber. Speed and velocity, even with a higher BC bullet is always a good thing and in my world, faster is always better.
This is how I ended up with a custom Mauser in 220 WBY Rocket fast twist, a pre 64 Model 70 in 257WBY, a pretty Mauser in 7mm Mashburn Super (7mmSTW and RUM won't QUITE fit the Mauser action, but the Mashburn does nicely, with a significant powder/power increase over a 7mm Remington or WBY) a highly tweaked and cleaned up 1917 in a wildcat 338/8mm RemMag (very similar to a 340WBY, and 340WBY ammo will run in it just fine) and a CZ 550, again much tweaked and tuned, in 416 Rigby which I can - and do - load to 416 WBY velocities.
I am exceedingly happy with my choices, others like their choices for their reasons. Not everyone has to be a speed slut like me
