Forming 257Roberts into 6.5x257

Hi, new here, I recently acquired a rifle from my deceased uncle, a sporterized Japanese Arisaka, rechambered in 6.5x257roberts. From comparing the brass that came with the rifle, 257 and 6.5x257 are pretty much the same except the mouth is opened up to except 6.5 cal. Would like to reload some newer brass, but was thinking all I need to do is fire 257roberts cartridges and that would form the brass to 6.5x257. I found a box of new Remington 257 Roberts at a recent gun show, I'm pretty sure this will work, but is this the right way and safe way. I have a set of RCBS dies (6.5x257) that came with the rifle. Does anyone here reload for this caliber?? Appreciate any info I can get, rich

Hello
Shooting 257 Roberts in a 6.5 x 257 is safe but not accurate and a waste of money.
You can just buy brass and run it up in the sizing die and the elliptical expanding ball will
open up the mouth of the brass.

https://www.gunbroker.com/item/754981605

http://www.calguns.net/calgunforum/a.../t-734555.html

Mike

OK, Thanks Skeettx, I was mostly concerned about safety, not accuracy. Figured it would be easier to fire form than run them thru the sizing die and possibly crumple some necks.

Redding makes a series tapered expanding plugs, look up those. They should expand without crushing neck/shoulders with proper lubing.

You are only enlarging .007" I don't think neck splitting will be a problem. If it will fireform it will size up. Use case lube in the neck and be generous.

Rich e just get a set of 6.5X.257 dies and load them up.
They come with a tapered expander ball.
I know because I have one.
One thing, slug your bore. Mine had a .268 bore.
I had mine rebarreled with a .264 bore and works MUCH better.
Enjoy it, Timney also makes a replacement trigger/safety that is a heck of a lot better than the stock Arisaka safety.

Thanks guys, I do have a set of RCBS 6.5X257 dies. The rifle was my uncles, we grew up together, to me he was like a brother, after he passed his son dropped off a couple of his rifles he thought I might like, one of them was the sporterized Arisaka, with some ammo and dies. Not being familiar with that caliber, I figured I'd best get some info on how to form the brass. So thanks for all the help.

You can fire form your 257 brass and then you have what you need. You can also neck down 7 x 57 or 8 x 57 brass with your RCBS dies. If using 7x57 brass the shoulder will have to be blown forward by fire forming with your first load, the 8x57 will come out just right. Several years ago I had a 26" Shilen barrel chambered to 6.5x 57 Mauser and installed in a 98 action. The rifle is a bit too heavy for a "packing around" gun, but I am saving it for when I get old and want to just sit in one place and snipe. I did hunt with it one fall and killed my 2 white tail deer and cow elk using Hornady 129 gr. bullets, it works well but has been waiting patiently in the safe since. I am not sure how strong your Jap action is, but I would think loads from Hornady book for 6.5 x 57 should be fine for you. JW