Even with current powders, you get next to no increase in performance with the STW. You need to make the BIG jump to RUM to get much bump in performance. I have friends who have problems with STW's. Theirs are finiky to load for.
My Mashburn does not seem to have the intermittant pressure problems you hear about with 7 Rems. If you chamber a 7 Rem so that the base of a 175 is at the base of the neck and chamber the Mashburn the same, the difference in useable case capacity difference is only about 3-4 grains given the same target pressure and using the same powders. My preference is RL-25. So throated, the 7 Rem you will have freebore with all lesser weight bullets.
The Mashburn, Weatherby, and Rem are all performance similar. The Mashburn has a longer neck than the Rem and no designed in freebore. In a pinch if I end up somewhere without ammo, I can shoot 7 Rem in it and make it work. Not recommended but doable.
The 7 Rem is currently under loaded from the factory compared to original loadings to about 58 K psi. because of gun variability, short neck, and the design to fit a 30-06 action that forces bullets back in the case and reduces powder capacity by up to 20 gr compared to a long loaded Mashburn (col. +/- 3.56"). The Mashburn is what the Rem and Weatherby should have been.
