Rifle stamped 762

[greywolf67nt]

A friend of mine brought me his rifle to ask what caliber it is.
No stamp on the barrel but running along the front of the chamber it is just stamped 762 and on the side of the receiver is Mod.98. The barrel isn't tapered it narrows in steps about every 1/3 of the length.
I have used the old Google box and think it is a Mauser in 7.62 NATO. Anyone know anything about these?
If it is some say you can use .308 Winchester in it? I have read that can be dangerous depending on head space.
Yes I know pictures would help but all I have is the crappy camera on my phone and nothing shows up.

 

[Potashminer]

I have owned two that sound like yours. They were Mauser 98, usually from WWII, that found their way to Israel by various ways, and were re-barreled to 7.62 NATO sometime in the 1950's. You should find some Star of David stamps on the receiver ring. The barrels duplicated the military 98 profile, so the rifle would have been reassembled with regular military wood and furniture. On both of mine, you can find the barrel manufacturer date on the underside of the barrel.
Lots of commotion about 7.62 versus 308 Win.
I bought a set of SAAMI spec headspace gauges for my 308's, 243's. Neither of my Israeli's will close on a SAAMI NOGO gauge, so they are in spec for 308 Win, so I have no hesitation in my guns using commercial 308 Win. Be aware that the military NATO 7.62 NOGO gauge is the same length as the SAAMI Field gauge, so 7.62 NATO chamber specs are longer than 308 Win SAAMI specs. Military specs generally give absolutely no consideration to reloading or re-sizing - the NATO ammunition is going to be fired once, the cases are usually made thicker than 308 brass and the case discarded.
From what I read, SAAMI, CIP and the US Army each report a pressure value for the 7.62 NATO; each uses a different way of measuring, at least two of them don't even measure at the same point, but all three report a result in "PSI", and, of course, none of the three results match...

 

[Baribal]

SAAMI and CIP don't regulate the 7.62X51, it's NATO themselves who does. The CIP and the NATO way of measuring the pressure (by transducer) are the same.
The cases drawings are similar, but the chamber drawings are different. The max. headspace tolerances and the throat are the difference.

Especially with strong bolt rifles, that's correct to assume that if the bolt doesn't close on No-Go it's correct to shoot .308 Win in it.