The take-down is surely 6.5x53R Dutch/Romanian, or .256 Mannlicher.

.265 is a typo.

There's a typo in the actual advert also, 6.5x52R.
...but there has always been a bit of confusion over whether or not the rim is included in the overall case length. Case is actually closer to 54mm, usually listed as 53.5mm long.

Regardless of the math, its the rimmed version of the 6.5x54 Mannlicher Schoenauer, and as such is a highly respected vintage hunting cartridge.