I was comparing the 7mm Rem. Mag to the 7mm Weatherby. The cases are practically the same dimensions.

The Nosler 4 reloading manual shows the Weatherby with (MAX)72.0 gr. of IMR 7828 with a 175 gr. bullet. The Rem. Mag. with (MAX)65.0 gr. of IMR 7828.
With the cases practically the same, does the freebore in the Weatherby allow this difference in powder charge?

Less resistance in getting the bullet moving.

Is this same principal the reason one can normally use a larger powder charge with the GS HV bullets than a bullet like the Nosler Partition?

Thanks for your input.

Well, you're right about the freebore and the charges, but the bullet differances I would lay at the foot of the bullets' varying construction. Some bullets have more friction or drag as they go down the bore. More friction equals higher pressures, therefore lighter loads are required to prevent excessive pressure. At least, that's how I see it. - Dan

I believe also that the difference in the shoulder angles would allow more room for powder in the Weatherby case.

A internal program that I have shows 90.6 gr of water for the 7mm W. and 82.9 for the 7mm Rem Mag.

Thanks . Even though they look alike , it is obvious they are not.