This IS interesting stuff... Had to dig out some books to clarify.
Military small arms of the 20th century, 1983 unabridged edition-Ian Hogg and John Weeks.
Pretty much the bible of WW2 military small arms identification.
(there are softcover editions available that are not as thorough and complete)
Also, The Illustrated Encyclopedia of Firearms-Ian Hogg.
And, the NRA gun traders guide, seventeenth edition.
I will leave out the Meiji30 (1897) because it doesn't really apply here.
The Meiji38 6.5mm was built with 2 lengths of barrel.
The variations were:
Meiji38 (1905) Infantry rifle, with 31.45" barrel.
Meiji38 (1905) Cavalry carbine, with 18.5" barrel.
Meiji44 (1911) Cavalry carbine, with 18.5" barrel, fitted with folding bayonet.
Meiji38 Sniper rifle, 6.5mm, 31.45" barrel, fitted with bipod, telescope sight
offset to the left, and turned down bolt handle.
After battle experience in Manchuria and China, the Japanese Army decided
that the 6.5mm cartridge was not lethal enough. A new 7.7mm semi rimmed
cartridge was then in use in the Type 92 machine gun. It was modified to a
rimless configuration, and redesignated the Type 99 cartridge.
The Meiji38 Sniper rifles, rechambered for this 7.7mm cartridge, were redisignated
the Type 97 (1937) Sniper rifle. Still with a 31.45" barrel.
Type 99, (1939) Infantry Rifle, 25.75" barrel. Was a Meiji38, rechambered to 7.7mm
and simplified for easier production. At this time the Japanese quit the old practice
of running 2 production lines for Infantry rifles and Cavalry carbines. Adopting the
Midlength, "Short Rifle" pattern as all the other Armies of the world had done.
So the Type 99 was never produced in a long and short variation.
Note, that none of these books list the 99 with anything other than the 25.75" barrel.
This fits exactly with what I have seen after looking at MANY Type 99 rifles.
Never seen one in anything other than the standard 25.75" barrel form.
But I have seen the 6.5mm Meiji38 in both short and long forms.
The Meiji30/Type 97 and Type 99, all served together in WW2, are very similar
to the eye, and are often confused.
Another interesting point. At the end of the war, when all the Japanese weapons
were collected in the armories, to be turned over to the US occupation forces.
The order was given to deface all the Chrysanthemum markings on the weapons.
As one of the last Imperial orders, and a final act of defiance, the armorers were
quite thorough. Using a torch to melt a puddle over them, an arc welder to weld
a bead across them, or just grind them off. It's the first thing I look for!
This is as far as my Data and Experience takes me.
Very interested to see some pics. Good luck and happy hunting,
