thanks guys not sure i understand yet....if I get 6.5x50 jap will the bullet be larger than a carc 6.5....i know that the case is different but the 6.5 carc is 6.5x52...and it is real sloppy at the end of the barrel.....won't a 6.5x50 jap be even sloppier ?
The 6.5 x 50 Japanese is
not the same as the 6.5 Caracano. The 6.5 Jap uses a .264 diameter bullet, the Caracano uses a slightly larger bullet due to its unique rifling.
The 6.5 x 50 Japanese cartridge was never chambered in any commercial rifle. It was ONLY used by the Japaense military.
Take your Arisaka to a competent gunsmith and have him gauge the barrel and cast the chamber. Many Arisaka's were GI "bring homes" during/after the second world war. Many were re-barreled or re-chambered for more (then) commercially available ammo. The very first centerfire rifle I ever shot was my cousin's Arisaka that had been sporterized and re-chambered for .257 Roberts.
Go to the webstes I had posted earlier. Interpret the Japanese kanji markings on the top of the receiver, that will confirm what model you have. With good markings you should also be able to tell when it was manufactured (within a range of years). If you see a "0 0" stamped ahead of the serial number that means that the rifle was designated "for school use ony". This means that for some reason the rifle was not up to spec for combat service - Unfortunately, I learned that tid-bit of information the hard way.
Be aware that the Type 38 (assuming you do have a 6.5 x 50) was first manufactured in 1905 and up through the early 1940's. Your rifle may have had CONSIDERABLE use, and the barrel may be "shot-out". Also some Arisakas have "chamber issues". Mine has excessive head space problems and if you are not a reloader this may not be satisfactory for you. Again, take it to a competent gunsmith to be sure you know what you have.