Spanish 1916 carbine

Bein new to spanish mausers, just have to get one to add to my mauser collection, i recently purchased one seein just pics of it its mismatched,good bore, reciever marked 1918 oviedo, was told it was original 7mm mauser chambering, good lookin rifle, are there any markings, specific dates on the oviedo that help to determine what caliber its in when it was rebarreled? I mean short of doin a chamber cast, like i say new to Spanish guns, any links to reference material or info would be appreciated,

The two likely calibers are 7mm and 7,62x51. A quick check at the muzzle will usually tell the story. Most of these rifles have seen a hard life, so check it well before firing.

The ones in 7.52x51 were all originally 7 mm Mauser with a working pressure of about 45,000 psi. The converted ones were meant to be used with the Cetme version of the standard 7.62x51 which is loaded to less pressure and about the same as the 7mm. If you have one of the converted ones do not use commercial .308 in it as it's loaded to a much higher pressure then the standard 7.62 is. I have seen bolt lugs set back by the use of .308 in them. Normal 7.62x51 ball seems to work OK in them. If your 1916 is in 7mm then any standard 7mm Mauser ammo will work fine in it.