I have a couple Arisaka actions and a couple decent barrels...one was cut to 18 " by a guy a while back and it was recrowned decently.
I wish it were a little longer but I'm considering putting a truck gun together. Thing is, I'd rather have the rifle chambered in a round I have dies for and the brass is affordable and available. Japanese stuff is neither.
Would you guys advise me reaming an Arisaka barrel to .260 Remington or to 6.5 Swede? (Or other suggestions?)
I'm leaning to the Swede b/c I have at lease 200 empty cases, dies, and other guns in this chambering. But I really don't know if the .260 Remington brass is expensive, easy to find, available, ... or has many loads on the shelf, etc.
Anyones input on this would help.

Right after WWII, there were tons of Arisakas rechambered to use the .257 Roberts case necked up to hold 6.5mm bullets.(6.5X57mm/ "6.5mm Spence Special")This coinversion worked great.

I see no reason at all why you can't use either a 6.5X55 or a .260 Remington reamer on your barrels. Both are bigger in all dimensions than the 6.5X50mm Arisaka, so shoulkd clean up the Arisaka chamber without having to cut anything off the barrel breech section.

Slug your bores. Some Arisaka barrels are as large as.268" in groove diameter. If yours are this big, theHornady 160-grain .268" RN bullet might shoot best.

Thanks for the reply. I am aware of the 6.5 X 257 conversion... actually thought I had one when I was given an old arisaka carbine and with it came a box of 6.5 X 54. I asked the guy who wanted to git rid of it if the gun actuall fired the 6.5 MS rounds, and he said it did but it shot poorly. After some testing and firing of the MS ammo i found out the arisaka chamber was merely shot out and the throat badly eroded. The MS ammo keyholed badly but funtioned ok. Just a sloppy chamber.
Anyway, I now have this 18" barrel in good shape, new crown. Also have a couple of decent Japanese type 38 actions and still have the working bolt from the shot out model 44.
I'm leaning towards the Swede for the reasons mentioned above.
Thanks though for the tip on slugging the bore. That would make things a little different but do-able.

I have read a lot about how strong these Arisaka actions were. They dont seem to be very plentiful though....can you find them pretty easily or have they all been scarfed up and fetch premium prices?

I haven't been shopping for them but I am seeing a few of the arisaka parts on e-bay .... also try GunBroker http://www.gunbroker.com/, GunsAmerica http://www.gunsamerica.com/ , and AuctionArms http://www.auctionarms.com/nonjavahome.htm
you may find a few specimens there