Get the Weatherby or the Mashburn. The homework has already been done. No sense reinventing the wheel as MANY have BTDT way before you even start.
The 7 Rem Mag has three drawbacks IMO:
a) Deep bullet seating (unnecessary in a 3.6" action like a rem 700 or M70)
b) neck is short
c) limited capacity.
You can't do anything to significantly improve the thing without too much hassle. The Mashburn is a FAR superior design in a belted H&H case.
If you want to max it out,then seat a 160 gr bullet to the base of the case neck,and put it in a 3.6" box.Throat accordingly. This is kind of like the free bore in the Weatherby.
After maybe 5-6 rifles built this way going clear back to the early 80's, I decided i don't want to roll that way anymore. I take the 7 Rem mag for what it is and built a Mashburn.....FAR superior and willing to please. Friend doing the same thing, have said the same things.
Headstamp brass? Get the Weatherby and problem solved.
But a pal who used to post here has killed all varieties of NA BG trophies 3 times over .. He is Dallas SCI member. He is working on Round #4 with a 7mm Mashburn Super and has traveled to Mexico and Canada several times with his hand loads the last 5-6 hers and never a problem.Killed a record book desert ram in Mexico recently on his second hunt.
He can afford anything he wants and today uses the Mashburn exclusively. With 175 gr TBBC's, he say it kills like his 300 Weatherby.
No one seems to mind that 7mm Mashburn brass is head stamped 300 win mag.
