6mm rem to 7x57?

[hh4whiskey]

Anyone necked up 6mm brass to 7x57? I have some 6mm, and new 7x57 is high. Any insights appreciated.

 

[Lefty7mmstw]

Anyone necked up 6mm brass to 7x57? I have some 6mm, and new 7x57 is high. Any insights appreciated.

The only issue I've had necking up brass is sometimes the necks can be a bit thin. I've done a bunch of 7rem to 338win and with a mid step at 30 cal it works fine. I also do 30-06 to 35whelen and I step at 338 there.
If you've got some 6.5 dies with a bigger body than the mauser case than slip your 6rems over the 6.5 expander button with a well lubed neck( rcbs or equivalent liquid or paste- NO spray lube), than repeat with your 7x57 die to finish the form. If you don't have any 6.5 dies, then try the 6 to 7 move in one step; if it doesn't like it, simply get a 6.5 button and install/ slip your brass over it in your 7x57 die then go to the 7mm button to finish. It's best to use new brass, but I've done range pickups for the whelen and it works too. Clean/trim your brass and load up. There are very minor dimension differences between the two rounds other than neck. I doubt you'll have to fire form but it could be done with regular loads in this case.

 

[Gunpoor]

The two cases have a different shoulder angle, so I don't know if you can just open the neck up and make them work. I have done some re-necking of cases but don't usually like to do it if there are cases made for the caliber I am loading. If the 6mmRem are Winchester headstamp and are in good shape I would take them off your hands at a reasonable price and then you could buy new 7Mauser brass.

 

[Gunpoor]

Here are some new cases for your 7x57 that won't break the bank....

Graf & Sons - 7x57 Mauser

 

[hh4whiskey]

Thanks for the Graf's link. I found some of the Prvi 139SP loads that I've ordered to shoot and keep brass. Went ahead and traded the (50) 6mm brass (RP) for (100) 358 225gr accubonds.

BTW: I had $0.39/case in the 6mm brass, and have $1.00/rd in the Prvi (shipped), so I think I'll come out okay.

Thanks for the advice on the conversion go/no go, though....good to know.