Reloading Question - Necking UP 257 Rbts to 7x57

Thread starter #1

NWS

Senior Member
I have some once fired factory 257 Roberts cases and no longer have the rifle. Need your opinions on Full length resizing and Necking Up in my 7mm Mauser dies. Cases will be trimmed and measured as required. OK to shoot in my 7x57???
 

bullgator

Senior Member
If done properly....yes. The 7 Mauser is the parent case to the Bob so it should be a go.
 
Thread starter #3

NWS

Senior Member
I know the 7 x 57 is the parent cartridge to the 257 Roberts. Most discussions you read about are necking DOWN the 7 x 57 to 257 Roberts. You never hear anything about necking UP 257 Roberts to 7 x 57. However it makes sense it would work just curious to see if anyone has any opinions on that. 257 Roberts has a different shoulder angle than the 7x57 however that should be taken care of when resized and necked up to 7 x57. Thanks !
 

Jester896

Senior Member
If not it would be once it fired fired :) i might have a slight concern about neck thickness or should I call it thinness

looking at the specs the shoulder angle is the same...The Rob is slightly longer and you could push in back...might anneal them first.
 
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Thread starter #6

NWS

Senior Member
You’re right. Shoulder angle is the same. I meant to say the shoulder length on the 257 RBis is longer than the 7x57. Should all come out ok after resizing and trimming. Might need to check neck thickness though.
 

chuckdog

Senior Member
I purchased a Model 70 chambered in 7x57 (2013 Shot Show Offering) and couldn't locate brass or loaded ammo anywhere I looked in the spring of 2013.

I already had a pile of .257 Roberts brass, so that's what I used.

Works fine.

In the past it was common to use the then plentiful 7x57 for .257 because the latter was so difficult to find. Never imagined it would someday be turned around.
 

JWF III

Senior Member
Just an FYI, Grafs has some in stock. From $23/50 for PPU up to Nosler at $83/50.

Otherwise, it should work. I 2nd the opinion on annealling and the worry of thin necks.

Wyman
 
Thread starter #10

NWS

Senior Member
I purchased a Model 70 chambered in 7x57 (2013 Shot Show Offering) and couldn't locate brass or loaded ammo anywhere I looked in the spring of 2013.

I already had a pile of .257 Roberts brass, so that's what I used.

Works fine.

In the past it was common to use the then plentiful 7x57 for .257 because the latter was so difficult to find. Never imagined it would someday be turned around.
Thanks!!!! I was wondering if anyone other than me has done this.
 
I've used 243 Win cases to load 260 Rem and used 30-06 cases to load 338-06 simply by resizing in die for the caliber being loaded without any problems. Should work same for 257 cases to load y,57.
 
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