necking down brass


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shamoo
February 5, 2012, 04:20 PM
I am just wondering if someone could help me. Ineed to neck down 300wsm brass to7mmwsm and iam not sure what to do. I have 7wsm rcbs dies but not sure if i can run brass threw them.

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rcmodel
February 5, 2012, 04:28 PM
1. Apply Case lube.
2. Gofer it.

There is such a small differance in neck dia between 7mm & .30 you won't even feel it.

The only problem you might have is:
The Whizzem cases have very thick necks to start with.

They may get too thick to release the bullet in the chamber with the necked down cases.
You may have to ream or neck-turn them.
So be sure and do some measuring to find out before you load them.

rc

shamoo
February 5, 2012, 04:31 PM
thank you

Strongbad
February 5, 2012, 05:08 PM
I've seen a lot of WSM cases that were nickel plated. If they're nickel, I wouldn't bother. Too many issues. Stiffer, they flake, harder on your dies etc.

If they're brass, run them through the resizer and go to work.

helotaxi
February 6, 2012, 04:39 PM
Imperial Sizing Wax makes it nice and easy. Like mentioned above, you almost don't even notice the difference between the neck-down and regular sizing.

A word of caution: The headspace dimensions are longer on the 7mm WSM than the .300 WSM by about 0.03". You'll need a way to control the headspace and use the first firing to fire-form the cases to the 7mm. It will move the shoulder forward a bit. This dimensional difference was intentional by Winchester to prevent chambering the wrong ammo.

jerkface11
February 7, 2012, 11:07 AM
If they've been fired aneal them first or you'll get some split necks.

LoonWulf
February 7, 2012, 01:51 PM
I neck up my 7mm brass to .30 then back down to 7mm slowly till i get a crush fit in the chamber of my 7 remmag, seems to extend my brass life a bit. I also anneal after the first firing. Since your starting with a .30 you can just slowly run them thru your sizer die till the bolt will close on a case with a little resistance, that should give you enough auxiliary should for fire forming.

shamoo
February 8, 2012, 07:21 PM
Thank you for the info. I bouhgt some nosler brass because i could not find norma. Just wondering what of load i should use to fire form 40 to 50% of a normal load ?

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