With 257 Robts brass not being commercially available is there another caliber's brass you could convert? 6mm or 7x57?

Perry

You should be able to just run 7x57 brass thru your 257 rbts fl die and be good to go. You might need to trim them back a little.

Made a lot of them out of some 25-06 brass in the 80s. . But, the 7mm would require less trimming.

30-06, 7x57, 6.5x57, 280, 270, to name a few can produce 257 Brass pretty easy..

My choice would be to purchase some PPU brass in 7x57 and run them thru the 257 Robts die, and outside neck ream, and trim to length, if need be.

I think HOrnady is making 257 brass now??

There are 3 families of brass which will provide basic cases for about 3/4ths of the cartridges presently available on the US market. the families are .222, 30-06, 300 H&H. the crucial dimensions are the head diameter and sufficient length. A few cartridges not of these three groups are the rimmed cases, a few 6.5s, the 404 & 416 based cases. So to answer the question, any case that has a .473" base diameter and length of at least the 257 Roberts can be formed. this would mean 257 Robt cases could be formed from 7x57 and 30-06, but the 243,7-08, 308 cases would be short.

Midway has in stock 6.5 X .257 Roberts brass.....a real simple run through the .257 Roberts die and go to the range.....it's not cheap.....

You could buy loaded ammo as well.....Midway has Horbady, Norma, and Nosler ammo in stock.....the Hornady ammo is actually less than the cost of the aforementioned brass.....it's under $30 a box.

Gunbroker has a lot of new .257 Roberts brass at $1.00 each

It also works find to run 6mm Remington brass through a .257 FL die to expand the necks. The shoulder angle is very slightly different, but it still works fine.

I've necked down plenty of 7x57 to .257 and that is probably the best solution in that the necks will be just enough thicker to make a marginally better fit in most Roberts chambers. The same applies to 8x57 brass, but of course the amount of neck-down is somewhat greater and wrinkled or collapsed shoulders can be a problem. Using either case may require trimming for overall length.

Using .30-06 or that family of brass puts the neck of the trimmed .257 cases partially in the shoulder area of the old case. This usually requires thinning the necks after reforming.

Somewhere in my loading shop is a set of RCBS forming dies to make 6mm Rem, from basically anything long enough with a .473dia case head.

The set starts with an 7mmX57 form and trim then a 257Rob then a 6m/244Rem and includes an inside neck reamer.

But with the off again on again production of 7mmX57 Brass some here would regard using 7mm brass to be heresy!

I have not seen that set in years because my brother traded away his 6mm Rem Rifle and I have not bought another one.
I will eventually build one but On a Long (30-06) length action.

Because building a 6mm rem on a 308 length action is as much an act of profound stupidity as building a 7x57, 8x57, 257Rob or 6.5x55Swede on a short action.

I don't have a lot, but how many do you need?

quote:

Originally posted by Atkinson:
30-06, 7x57, 6.5x57, 280, 270, to name a few can produce 257 Brass pretty easy..

My choice would be to purchase some PPU brass in 7x57 and run them thru the 257 Robts die, and outside neck ream, and trim to length, if need be.
I think HOrnady is making 257 brass now??

How do you "outside neck ream" ?

You know what he means.
For my Ruger 77, 257, it did not require neck reaming, or turning, as the chamber must be big enough to handle reformed brass. Once I got some real brass, in the 1980s, I no longer used the reformed brass.

I have got a good bit of once fired stuff if you need some. Mostly Nosler, some RP.

I used to make them from military 7.62 blank brass.

What's the matter with just using 6mm Rem brass or is that is short supply or forgotten also...haven't checked.

LUCK

Lemar28,
You use an outside neck reaming tool, Mine is from RCBS..I have outside neck ream my ,223 cases fir nt 6x45 that has a zero tollerence bench rest chamber. I also used it on some tight chambered 7x57s Ive had over the years and a few other calibers..I seldom however inside neck ream cases..

quote:

Originally posted by Atkinson:
Lemar28,
You use an outside neck reaming tool, Mine is from RCBS..I have outside neck ream my ,223 cases fir nt 6x45 that has a zero tollerence bench rest chamber. I also used it on some tight chambered 7x57s Ive had over the years and a few other calibers..I seldom however inside neck ream cases..

outside neck ream- Outside turn maybe?