[LVSteve]

If the rifle has 7.62 written on it, then it is a converted Spanish 1916. I cannot see it in the photos provided. If you go to the Spanish Mauser site. http://masterton.us/Spanmauhome , you may be able to tell if the barrel has been set back for rechambering by comparing yours with the detailed pictures. Try at the bottom of this page. http://masterton.us/Unmarked1916

 

[LVSteve]

I am still baffled as to how the serials on the receiver and barrel can be the same if it is NOT in 7mm Mauser or 7.62 CETME. Either the barrel is sleeved, which seems unlikely, or you have 6.5 rounds rattling down a 7mm pipe.

Have you tried a muzzle test? Take a 6.5x55 round and poke it into the muzzle. If it swallows the whole bullet and only stops at the case, then it is NOT a 6.5 mm bore.

Is there no writing at all on the top surface of the receiver ring above the serial number and vent hole?