RE: Argintine Mauser?
eldeguello covered it nicely (as he always does). I've got one of these rifles too, though mine was made by DWM (Deutsche Waffen und Munitionsfabriken). It's all original except for the crest havingbeen ground off. My grandfather bought it years ago and I ended up with it when he passed away in '73. I use if for hunting occassionally, but nota lotas I don't care muchfor hunting with iron sights.
The cartridge is in factthe 7.65x53 or 7.65mm Argentine. Norma makes ammo for it. Imostly shoot handloads inmine using150 gr.Hornadyor Sierra bullets. Sierra bullets are .311" in diameter while Hornadys are .312". I getbetter accuracy with Hornadys.