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Forming 257 Roberts brass

25 May 2021
@ 01:31 pm (GMT)

Shaun Milo

I know that 257R can be formed by necking down 7x57 brass or necking up 6mm brass. I saw some 6.5 x57 brass for sale, could this be necked down? Thought I saw somewhere that the neck would be too short? Any help would be appreciated.



26 May 2021
@ 08:32 am (GMT)

Nathan Foster

Re: Forming 257 Roberts brass
Hi Shaun, the case lengths are basically the same (56.7mm).

The length to the shoulder / neck junctions differ.

The 6.5x57 is 49.3mm.

The .257 is 48.56mm.

In other words, you will need to reduce the shoulder length of the 6.5 brass to fit your chamber.

Hope that helps a bit.
26 May 2021
@ 01:59 pm (GMT)

Shaun Milo

Re: Forming 257 Roberts brass
Thank you sir for the quick reply. I did not know if different shoulder angle made a huge difference. Do you think that just putting them through a FL roberts die will work or would I have to first create a false shoulder?


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