there's no way I can think of to determine what the real weighting factor should be.
I found one thread at another site where one guy did the following calculation to categorize how "overbore" a cartridge was.
Case capacity (grains in water) divided by Bore Area (pi times Bore Radius-squared). So, when I apply that to the 264WM, I get a quotient = 1,526. When I tried it on a 30-378 Wby, I get a quotient = 1,693.
Then, he compared his overbore ranking to what QL listed as the default weighting factor that appears in QL for that particular cartridge. For the 264WM, I got = .50; for the 30-378 Wby, I got .52.
His overall conclusion seemed to be that he didn't feel like QL's default weighting factor always took the "overbore-ness" into consideration.
Interesting. YMMV