I am looking at a trade that would net me a nicely sporterized Arisaka in 7.7 Jap. If it doesn't shoot or if I get bored w/ the 7.7, will a '06 length round fit in the Arisaka??

It's been done, but lots of folks say it isn't safe, as the base diameter of the Arisaka is a tad larger than the .30-06

I tried a dummy M2 Ball round in my (not so nicely) sporterized Model 99 Arisaka. The magazine is about 1/4" too short to accommodate the 30-06 round with a 150 Gr FMJ.

OTOH, the 7.7 is a versatile round the can do most of what the '06 can, and reasonably priced boxer brass/ammo are available from Grafs' and Hornady.

I've read that the 06 head is smaller and requires at least .375" set back of the barrel to make it safe. IMO this would make the chamber area of the barrel too thin. If I change the caliber I would install a new barrel.

Is the mag the only thing that is too short?? Will the bolt move back far enough to eject a loaded round?? Weatherby cuts a relief in the front part of their ejection port. I don't want to do that to this action (it is already nicely polished and blued).

the 7.7 jap bore size is nominal .311 NOT .308.
so if you keep the barrel, whatever you chamber it in must use a .311 bullet. the 7.7 chamber IS a bit bigger around than the '06 case. you can still buy norma brass for 7.7, by the way, and dies are readily available. see if that rascal is a shooter as is before considering a re-chamber or other heavy work. it's just about .30-'06 equivalent with good loads. the 99 is one tough action. you might consider a wildcat based on the remington or winchester short action magnum. check out the specs. but above all, get a qualified stud to check out headspace, boltlug setback and such before proceeding.

After the war, a lot of 7.7 's were brought back to the US. and an .06 chamber reamer run through them. Not an exactly accurate combination, but it worked. I made a nice .270 out of one by putting a cheapy barrel from Gun Parts on it, turning and rewelding the bolt down and carved a stock for it,. I shot a nice ram on Pikes Peak with it and then sent it back east for my niece to hunt whitetails wit. She still has it.

Did they actually have a barrel already threaded for 17-whatever threads per inch?

No, you buy a blank with no threaads, and thread it.

.311" bullts are not a problem as I reload 303 Brit for a neighbor. If this doesn't shoot I was thinking about a 30 Newton w/ a new barrel. This may be a bit long for the reciever, my data shows .015" longer than an'06.

A pawnshop in my area has a nice custom Type 99, with
a nice stock and a side safety, price is 249.95, if I remember
correctly. I would rather have a nice custom Type 38, but
these guns are getting few and far between, so if you find
a nice one scoop it up. I have seen Arisakas rebarreled to
almost every caliber you can think of 22-250, 250 Savage,
300 Savage, 358 Winchester, 243 Winchester, etc. they are
not an attractive gun, except in the eyes of us gunheads.

I have a Type 99 Arisaka. In the early days, I couldn't afford Norma 7.7 brass, or ammo, so I sized down 30-06 brass in my 7.7 dies, then trimmed to length. The cases would last about 2 firings before cracking just above the web. Too much hassle, Graf's now offers new unprimed 7.7 brass, at a much better price than Norma. I haven't fired the rifle in years for some reason.

I'm gonna make the trade. If it is a shooter I will be happy w/ a 7.7. If not I will rebarrel it to something that will fit. I'm gonna buy the 30 Newton dies anyway cause they are only $20. The dies may sit on the shelf for 10 years until I find a doner action to make a nice 30 cal screamer.

A lot of 7.7 rifles were rechambered to .30-06 by the Army right after WWII and issued to South Korean troops. Not the most accurate, but a whole lot better than a set of numchux. Good enuf for govt work with milsurp and factory ammo.

Grafs also sells loaded ammo (Hornady) for the 7.7, at about $20/box.