my reciever did have a 30 cal marking
Haven't checked this thread for a day or two . . .
Yes, as others have said, it may be chambered for 30-06. I would also suggest a chamber cast at this point.
Why is a South American rifle chambered for the US service cartridge, you may ask? In the 1950s, the US negotiated an end to the wars that had been going on in South America for almost a century. One of the parts of the treaty was that the US would provide the military supplies for the region (formerly, many were supplied by Germany, Austria, and Belgium until WW2). This is why many bolt action Mauser rifles coming out of South American countries are chambered in 30-06, most of the countries went on a massive changeover project (before that most were 7X57 and 8X57, the Argentines were the odd ones with the 7.65X53).