Making 7 WSM brass from 300 or 270

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b72471

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I have read a bit on this and it seems the 300 WSM is a better choice, Im not sure I agree. When you look at the drawings necking up only requires .007 expansion of the 270 WSM.
Sooooo Im thinking if I were to expand the neck only far enough to allow seating a bullet that would snug up to the lands with firm pressure when chambered for fire forming
It should work???? Has anyone tried this?
Thanks.
PS the rifle and 270 brass should arrive this coming week, and I will have some factory rounds and brass, however I will need additional brass.
 
Bill; The 7mm WSM case is a bit longer to the shoulder than is the 270 or 300 WSM [around .038" longer]

If you try to make 7mm WSM cases from 270 WSM cases by simply necking up, you will have a lot of excess headspace that you do not want.

If you take 300WSM and size them down to 7mm WSM, you will have a false shoulder, which makes it viable.

If you "jam" the bullet into the lands to fireform the 270 WSM cases, it may work OK....I have not tried this with this chambering, but it worked when I made 30 Gibbs from 30-06.

Regards, Dave.
 
7wsm is a real PITA to make. Currently on 60 of 100 cases that I'm forming from 300wsm Winchester. Neck down to 7mm, load with 16gr unique, 33gr cream of wheat, top with a ball of paper towel and fireform. Tumble clean, resize neck, outside neck turn, trim to length, resize in deck die, anneal, debur and chamfer....done. Sure wish a person could just go pick up a couple bags of it at the store....maybe one day they'll make brass again.
 
Well Gentleman I received the 270 WSM 1X brass today. So I just had to reinvent the wheel. On checking the neck of fired 270wsm brass I found the sizer in my 7wsm die would slip into it with just a very slight resistance so I ran it through the 7wsm die, primed and added 61grs of H4831 seated a bullet out just far enough it took a bit of pressure to move the bolt handle down to its full closed position. Stepped out the door and fire a shot. Sooooo on going back into the den I compared this brass to a new 7wsm brass, the fireformed brass was perfect. Measuring the fireformed brass was 0.003 longer, neck thickness was 0.015 same as the new 7wsm brass (I'm don't know why) neck thickness was consistant about a 1/2 thou variance. Inside the neck there was NO doughnut I could see or measure. So for me this is an easy way to go if I can't find the 7 WSM brass. cdn shooter I like the cream of wheat fireforming and use it on PPC forming, this rifle of course is a hunting rifle so I won't need to be fireforming that many rounds.
Thanks guys for your input greatly appreciated. Dave you had a great year hunting, I'm still at it.
Bill
 
Bill; Glasd it worked out for you!! I suspected it might if you "jammed" that bullet a bit.

As I stated earlier, I made a bunch of 30 Gibbs brass from 30-06 the same way....can't remember losing any cases, either.

Yes, my season has been great so far, but I still have an antlerless Elk to find. My BIL and I both have tags.[after Dec 1]

Hope you can make your season work. :) Dave.
 
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