Thread: 7mm wsm to 270wsm sizing

I have been gifted a batch of Norma brass that is head stamped 270wsm but has been sized up to 7mm wsm, some is virgin unfired and some has been fired once.
With the regaining of my old 270wsm I am keen to reclaim this brass for use in it.
Is it a simple matter of annealing the brass then full length sizing in a 270wsm die and then checking trim length ?
Strangely enough theres heaps of info on forming 7mm wsm brass from 270 or 300 wsm cases but nix info on going the other way

Thatd be quite a bump to go from the 7 to the 270. The shoulder on the 270 is further back than the 7mm. Just try one, anneal it, run it through your die and check it out. I feel like there will be a bit of damage to the case on the neck and shoulder

@grandpamac I feel like if anyone knows a way you might ? Any suggestions ?

I'd be surprized if it was anything less than difficult, like @keengunNic says, a lot of excess brass that needs to find a home.

Originally Posted by 7mmwsm

Sell the 270 and buy a 7mm. Problem solved.

Unlikely, but if it really is doomed to failure then I have a batch of 7mm wsm Norma brass for @223nut

Get a 3006 nro

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Originally Posted by NRT

Get a 3006 nro

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Nro was meant to be bro ,bro

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Maybe give it a try it is a big shoulder bump but iv seen creed brass made from
308 so what's their to loose I went 300 down to 270 wsm with ease

Hmm, depends if its actually been fired in a 7mm wsm or a 7/300wsm which are popular with the target crowd.

If it's a 7/300wsm chamber then it will be easy to go back down to 270.

If it's a true 7mmwsm chamber maybe not so easy.

The unfired vs fired brass will give the answer.

Originally Posted by dannyb

@grandpamac I feel like if anyone knows a way you might ? Any suggestions ?

Greetings dannyb,
If the .270 WSM brass has just been necked up to 7mm and has not been fired then there should be no problem in necking it back down. You should check if the shoulder has been moved forward. You can do this with a comparitor. The difference in length to the shoulder is 0.038" or 0.96mm longer for the 7mm WSM. The fired stuff is a different matter. If the cases were just necked up without forming a false shoulder and fired in a 7mm WSM chamber then they would have been fired in a chamber with grossly excessive head space. This could have weakened the case body just ahead of the web and can lead to a head separation. To be safe these should be binned.
Regards Grandpamac.

Originally Posted by grandpamac

Greetings dannyb,
If the .270 WSM brass has just been necked up to 7mm and has not been fired then there should be no problem in necking it back down. You should check if the shoulder has been moved forward. You can do this with a comparitor. The difference in length to the shoulder is 0.038" or 0.96mm longer for the 7mm WSM. The fired stuff is a different matter. If the cases were just necked up without forming a false shoulder and fired in a 7mm WSM chamber then they would have been fired in a chamber with grossly excessive head space. This could have weakened the case body just ahead of the web and can lead to a head separation. To be safe these should be binned.
Regards Grandpamac.

That's very helpful as I have 30 virgin cases that have been necked up to 7mm but unfired so these at least should be salvageable for me

Unfortunately or fortunately for @223nut I also have 50 cases that have been fired so looks like he's got some extra brass

Sounds good to me... I need to get round to emptying a few more of my own

Originally Posted by 223nut

Sounds good to me... I need to get round to emptying a few more of my own

Don't be in too much of a hurry as Powder and pills are scarce you need to come up for another hunt anyways

ok so I just have to ask....what happens if/when you chamber one of the upsized cases and close bolt????
will it do so easily??? that SHOULD tell if chamber has been large on previous rifle....also if your chamber is on generous size to begin with it may not actually be such a big issue...maybe???

Originally Posted by Micky Duck

ok so I just have to ask....what happens if/when you chamber one of the upsized cases and close bolt????
will it do so easily??? that SHOULD tell if chamber has been large on previous rifle....also if your chamber is on generous size to begin with it may not actually be such a big issue...maybe???

Will have to wait and see both rifle and brass are in transit still