Can anybody tell me what the 25x61 Burnett Magnum is?

Just read the auction listings, "a custom belted magnum similar to .264 Belted Magnum".

Unfortunate, but "similar" will not do since I'm really attached to my eyes and fingers! The seller sent me some chamber dimensions and I still don't have a clue. Interesting that unlike the similar .264 magnum this cartridge has a bullet dia. of .261. Of course, 6.5s tend to some weird configurations.

Bullets made for 6.5x58R Sauer are .261" daimeter.