Factory muzzle brakes on different calibers

I've got a 270 WSM and the inside diameter at the end of the brake is about 0.415 in. A 300 RUM and the inside diameter at the end of the brake is about 0.335-0.340in. A 338 WM and the inside diameter at the end of the brake is about 0.375 in. How and/or why does the brake on the 270 WSM have a larger diameter? Could a break off a 300 RUM be used on a 270 WSM? At first is would seem that a 30 cal brake would be way over bore fore a 270 cal, but it would actually be a step down in this case? I am asking because I am attempting to build another 270 WSM and I have a barrel and now an extra 300 RUM brake.

Thanks,

JBS

Now that is puzzling. Kinda defies logic. Course I'm not in the brake business and there's probably some gas management formulas that I'm ignorant about.

Personally I would try the 300 RUM brake with your new 270 WSM. If it doesn't perform well, your not out much