I saw a mauser style rifle at a gun shop recently and it had 257X6.5 on the barrel. My question: Is this a 257 caliber bullet in a 6.5 jap casing? Were can i get dies and relaoding data?

I have always wanted to get into wildcating but never had the funds for a custom rifle. This one seems nice and clean and for a good price. The 257 caliber would fit nicely for what i would use it also. The action does not look like an old military mauser, but more like a custom action. I think i remember it having "interarms" or something similar stamped on the action. Most of the top of the action was "open" and there was not any space to D/T on the top, so it was D/T for a side mount "like an old weaver style"

Any information would be helpfull.

The 6.6/257 Jap rifles were normally the 6.5 Jap rechambered to use easier to get 257 brass, thereby creating a 257Robts with a 6.5mm bore, I'm not sure what the one you're looking at would be, whether a 257 bore with some form of 6.5 case (x55,x54,x53,x57 ??? ) or as I've described above. More info needed, get thee back to the gun shop.
Dies for most iterations of are available from one or other of the die makers CH4D, RCBS, Redding & Hornady all have lists of wildcat dies they already have tooling for & if they don't have what you want will produce same with 3 fired cases or reamer drawing etc & a pocket full of shekels.
Steve

Two points:

As said, the Japs that did not have ammo available were rechambered to .257 Roberts cases which needed a 6.5 bullet loaded... no big deal but this one, you seem to indicate is not a military... ??? O.K.

#2). In Europe they do it backwards. In US the .30/'06 necked down to .25 became the .25/'06. In Europe it would be something like the .30/'06/.25. This is fun with Martini's. You look at a .450/375 and think the bore should be .45 but with their system it should be 3/8's/.375...

SO "cast the chamber." You can do it with melted sulfur from the garden store. Heat it gently until it melts. No explosiveness but if it catches fire IT STINKS. Shove the lid on the pan to put the fire out... Pour into chamber with bore blocked by tight patch. Let cool. Minute or 3. Gently shove out... Measure... If you leave a little barrel ahead of the chamber you can also guage bore and throat condition.

This is the fun part. "What is it?" Figure it out... Might be able to cut the price if brass is a pain. Nothing Walmart would be interested in. Luck. Happy New Year.

This is what ramrod340 said on an earlier thread " Wildcats And Their Development - 6.5X257 or 257 Jap Question"

quote:

A 6.5x257 is a 6.5-7x57. Since a 257 is a necked down 7x57. The jap was a 6.5x50. Around 57grs capacity vs 47. Within a grain or two of the 6.5x55. Yep dies are available. I believe the 6.5x257 is different in the shoulder area from a 6.5x57Mauser. My first rifle was exactly what you have. I hunted a year or two as a 6.5jap then made it a 6.5x257.

on a commercial mauser? dont see anyone doing any type of jap based cartridge on that action. most likely i would say its a 257-6.5x55. Only other "6.5" that i can think of would be a 6.5 Rem Mag, and a 25x6.5RM would be fairly nifty! Heck either one would.

The .257 case necked up to 6.5mm was a popular conversion right after ww2 in arisaka surplus rifles. I've seen a few custom mausers done with them too. Seems to have fallen away for the 6.5x55 and the .260 rem. I have seen the same case improved like ackley did but the 6.5-284 is a better choice (IMO). I have heard that mauser chambered some 6.5x57 mausers. I have yet to see one. Should be a great deer round.