The Argentine Mausers are very high quality and many are still in extremely good condition.
I picked up a couple of 09's and a 91 last year. All three are in the original 7.65 x 53 caliber.
http://forums.gunboards.com/showthread.php?t=31147
Many believe the 7.65 Mauser was the best caliber that any Mauser was chambered in. The ballistics of the 7.65 x 53 are almost identical to the 7.62 x 51 Nato round.
http://www.surplusrifle.com/argentin...ammunition.asp
Here is a link that includes information about the 09 and 91 Argentine Mausers. Good luck
http://www.surplusrifle.com/argentin...bine/index.asp
http://www.surplusrifle.com/argentine1891/index.asp