I love my Vanguard in .257 Wby Magnum but the Wetherby and Norma brass are so expensive. Does anyone have experience in necking down the 7mm Rem Mag brass to .257 Wby Magnum? Can you simply full length size the .257 Rem Mag brass in a .257 Wby Mag die?

quote:

Originally posted by Red C.:
I love my Vanguard in .257 Wby Magnum but the Wetherby and Norma brass are so expensive. Does anyone have experience in necking down the 7mm Rem Mag brass to .257 Wby Magnum? Can you simply full length size the .257 Rem Mag brass in a .257 Wby Mag die?

Do it in "stages, a little at time, and trim to correct length.

I tried doing the same thing with 7mm Mag R-P brass and found it can be quite dangerous and causing excessive chamber pressures. There is a HUGE difference in the internal capacities between R-P and Weatherby or Norma brass. Full loads that were developed in a rifle using Wby brass will see very high pressure when using R-P brass. The 7MM Mag brass also comes up 0.05 short in length. Yes, it can be done but throw the loading books out the window as most reloading manuals have developed the loads with Wby brass. They will resize very easily. Run the brass thru your 257 seating die first and then through the sizing die. Works great. Be very careful when reloading and changing any major component where full loads have been established.

Just a thought. When you reduce the neck diameter that much, will those cases have a thicker neck than factory cases? May need to neck ream the downsized cases.

Necks end up OK. Factory chambers are sloppy.

+1 to what 30378 said. This is definitely the time to start with a minimum load and work up carefully, but this reduces the cost of the brass quite a bit.

LWD

quote:

Originally posted by buffybr:
Just a thought. When you reduce the neck diameter that much, will those cases have a thicker neck than factory cases? May need to neck ream the downsized cases.

YES, I was just about to add that to my post.

I was going to suggest using 264WinMag brass instead as there is a smaller change in neck thickness and thus less need for dealing with a thicker neck.

But if you DO need to change the neck don't ream it, use a piloted outside neck turner.
a generally cheaper tool that does a better job and as quickly as you can change pilots it can be used on another cartridge...



AD

I think I have some 7mm Weatherby brass-once fired if you need it. Let me know if you are interested and I will check and see. I think the Weatherby brass is Norma brass. Definitely good stuff. Tom.

Also...I've found....at least with my dies, that you should use VIRGIN BRASS. Even once fired seems to harden the shoulder/neck area enough that getting a uniform case is difficult. You'll want to start at least 3.5 grains below your favorite load with wby brass.