Resizing Norma brass to 7WSM

[airborne_trooper]

Hello my local sportsman has both 270 and 300 WSM in stock. Im looking for some help on how to resize it to 7 WSM. I have both Redding or Forster FL dies in 7 WSM. Should I neck up from to 270 or neck down from 300. I know the shoulder has to be pushed forward and fire formed. I'm not sure how to do it! If anyone could break it down step by step would be great!

Thanks
Jet

I'm giving up hope on finding Winchester 7 WSM brass

 

[whatwind?]

The neck is longer on both the 300 and 270wsm, won't fit in normal 7wsm chamber

 

[Steve Blair]

The neck is longer on both the 300 and 270wsm, won't fit in normal 7wsm chamber

No, that's not correct. All three cases are exactly the same length. The 7mm WSM shoulder is ~.04" further forward compared to both the .270 and .300 WSM. You can make any of the three from any of the others.

 

[Steve Blair]

Hello my local sportsman has both 270 and 300 WSM in stock. Im looking for some help on how to resize it to 7 WSM. I have both Redding or Forster FL dies in 7 WSM. Should neck up from to 270 or neck down from 300. I know the shoulder has to be pushed forward and fire formed. I'm not sure how to do it! If anyone could break it down step by step would be great!

Thanks
Jet

I'm giving up hope on finding Winchester 7 WSM brass

There are several ways to do this. You could form a false shoulder on the neck and fire form. This would be the easiest way with .300 WSM brass. Or, you could neck .270 WSM brass up to 7mm and seat bullets to jam into the rifling, holding the case against the bolt face. Either would work.

 

[fguffey]

No matter how the case is formed and fired the case will shorten from the case mouth to the case head. This is one of those believe it or not moments. The 7mm WSM is a short neck case meaning after forming the neck will be shorter. Then there is the other part, the shoulder of the parent case will not move, part of it will become part of the case body and part of the neck will become part of the shoulder.


Again, I have formed and fired cases that shortened .045” from the end of the neck to the case head. That may not seem to be a problem for most but when I started the case neck length was .217” long.


Point? I would start with a longer case.


F. Guffey

 

[Steve Blair]

Point? I would start with a longer case.
F. Guffey

What case would that be, Frank? I've fire formed hundreds of Norma .270 WSM to .300 WSM and resultant cases are ~.020-.025" under maximum SAAMI length. Note that SAAMI specifies case length as 2.100"-.020", so formed cases are pretty close to spec.

Regardless, the OP asked specifically about forming either .270 or .300 WSM Norma brass to 7mm WSM. Either of those is fairly simple to do. Let's try to help him rather than discussing mythical cases.

 

[fguffey]

Point? I would start with a longer case.

Click to expand...
No, that's not correct. All three cases are exactly the same length. The 7mm WSM shoulder is ~.04" further forward compared to both the .270 and .300 WSM. You can make any of the three from any of the others.

I went back to determine who posted the difference in length in the cases from the shoulder to the case head,; it was you. A very popular answer on a reloading forum is ‘brass has to go somewhere”, I am the only fan of wondering where the brass is going to come from to fill the .040” difference in length when forming and firing. Again, I have no ideal how this stuff only happens to me (one more time), I have had cases shorten .045” when forming and firing. I knew the case was going to get shorter and I knew where the brass was going and coming from.


I did not like the short necks, there is an infarction with neck te4nsion on reloading forums, I have bullet hold, I want all the bullet hold I can get. One more time, I would not use the two options the OP listed. I would find longer cases.


F. Guffey

 

[fguffey]

One more time, part of the shoulder will become part of the case body and part of the neck will become part of the shoulder. The shoulder on the parent case will not move.


F. Guffey