Originally Posted by DesertMuleDeer
One other thought: if we are going to take the risk of making extrapolations regarding case capacity and pressure, why not use the 7mm Weatherby to compare? It is pretty much identical case capacity to the 7mm Rem Mag and there is plenty of pressure tested data showing it in the 3100-3200 fps range with 160s, which would make more sense of the data.


DMD: 7mm Weatherby's have freebore,which is similar to adding powder capacity,and the case tis loaded to higher pressures in both factory ammo and hand loading data.

As I recall the cases themselves are a bit lighter and have somewhat more capacity due to head design vs most 7 Rem Mag stuff which is heavier through the head design, and holds a bit less powder.

Plus a lot of 7mm Weatherby data is shown with 26" barrels.

All these little things add up to show a bit more velocity for the 7mm Weatherby, despite similar case capacities. Just the pressures alone can make a difference.

If we long throat a 7 Rem Mag this starts to level the playing field,and IME the 7 Rem Mag comes closer . One I had recently took about the same charges as a 7mm Weatherby with 160 gr bullets and H4831. The silly thing would not shoot well until I approached 7mm Weatherby data..... smile



The 280 Remington is overbore.

The 7 Rem Mag is over bore.