Why Krieghoff chooses one bore size and Perazzi chooses another?

If there really is a science behind the size of our shotguns? All the gun manufacturers seem to have their own favorite bore sizes. I have my favorite shotguns but I am not so sure that was because of the bore size. My favorite pattern came out of a .729 Perazzi with a 42 choke.

 

Everyone is looking to make a better mouse trap, From Stan Bakers .800 bore, Kohler tried the .750 bore Browning is stuck at .742 my opinion is there is a right load for all of them. you just have to figure it out. Even a Wilkonson tuned barrels will pattern shot with a select load the best.

 

It's gotta be sealing pressure vers drag. Have the wad just contact the barrel without to much drag...least that's my .01