257 Roberts Brass

[HammerB1]

I can't seem to find any 257 Roberts brass available. BUT, I have approx. 400 6mm rem cases available. Need help in the process of getting it there. How far to size up? Annealing? etc.?

 

[MNbogboy]

You may have very little work depending on the condition of the brass...
Try running one thru your 257 die as is...Make sure to use plenty of lube and on the inside of the case mouth for the expander....You may not need to anneal....Your cases most likely won't even need trimming to begin with...
I make all my brass for my 257 AIs and 6.5-257 Roberts from longer stuff like 270 & 06 cases which is indeed more work but I get the neck length I desire that way...
The case dimensions of the regular Roberts and the 6mm are so close that you should be good to go after one sizing and one fire forming...

Good luck,
Randy

 

[HammerB1]

You may have very little work depending on the condition of the brass...
Try running one thru your 257 die as is...Make sure to use plenty of lube and on the inside of the case mouth for the expander....You may not need to anneal....Your cases most likely won't even need trimming to begin with...
I make all my brass for my 257 AIs and 6.5-257 Roberts from longer stuff like 270 & 06 cases which is indeed more work but I get the neck length I desire that way...
The case dimensions of the regular Roberts and the 6mm are so close that you should be good to go after one sizing and one fire forming...

Good luck,
Randy

Thanks Randy,
The 6mm rem brass I have is once fired and has already been resized, trimmed and neck turned for my 6mm rem. That being said, I have tried just resizing to 257 Roberts and after fireforming, primer is sticking halfway out of cartridge.
Next, I neck sized up to 270 then back down to 257 to create a false shoulder then fireformed and same thing.
Did I not get enough shoulder tension to take the impact of firing pin or is there something I'm doing wrong?
I have fireformed many other cases doing this same procedure and has worked flawlessly. Also worried about overworking the neck.
Brian

 

[MNbogboy]

It sounds like the two chambers (or dies) differ quite a bit...I have also used the 270 expander to create the false shoulder on brass that is too short and it worked great ...Try adjusting your die neck sizing only enough with the 257 die until you definitely "feel" the resistance when closing the bolt on the sized brass...

 

[mtwarych]

Somebody on the for sale reloading section is selling 257 Roberts brass brand new.

Maybe worth a look.