I just read an article in some gun mag that briefly mentioned original military loads in various military calibers. Is there a place one can look (or someone can just tell me) where to find the original 7x57, 8x57, 6.5x55 and 7.62x54R load data?

I'd like to restore a few cheap guns out there and fire them with original spec ammo, just for kicks and grins.

Thanks a bunch

120mm
Try looking in a "Cartridges of the World".
They have info on most all the old cartridges. I would however check their loading data with current loading manuals in case of a misprint.
Also check a "SHOTGUN NEWS" or a "GUNLIST". You can buy original ammo for many surplus rifles.

I tried last night to get back in on the C. E [ED] HARRIS Handloading Library on Line but, it must have been shut down for the weekend.

DURING THE DAY type into your brouser:
C. Ed Harris Handloading Library Online
This is not a web sight so you need to go in through the "back door". There is a long list of interesting topics.

"Mauser Bolt Rifles" by Ludwig Olson has the specs for every cartridge ever fired through a Mauser bolt rifle. it does not tell what kind of powder but it gives the various bullet weights and muzzle velocities for every round.

The four rounds you listed ALL started out with round-nose bullets, as did the .30/40 Krag and U.S. .30/'03, predecessor to the '06 (220-gr. RN)!

The 7X57mm shot a 173-175 grain RN @ 2200-2300 FPS; the 8X57 used a 236-gr RN @ 2200 FPS, the 6.5 X55 used a 160 to 165-grain RN at 2300 FPS (all vels approx, varied by country). I forget the original bullet weight of the M1891 Moisin-Nagant load.

I believe the 7.62x54R used a 150gr. bullet at 2880fps (Russian loading). The finnish used a 166gr. bullet at 2540fps and a 200gr. at 2250fps. The M39 sights were set for the 200gr. loading at 150/300m. At 100yds, the Barnaul 203gr. FMJ/SP shoots about 4" high in my M39.