After owning/shooting/hunting a few 7x57's over the years (Ruger 77RS & #1RSI, & a '93 Mauser), I was attracted to the 6.5x55, since I knew the cartridge is regularly used effectively by Scandinavians on their Elg (our Moose).
Soooooo, I got myself a modern 6.5x55 - a Winchester M70 Featherweight - which turned out to be the most accurate of the bunch, and dropped everything I shot at, here in the US, tuit' suite.
I found the recoil to be somewhat less (160gr 6.5 boolits vs the 175's I was using in my 7x57's), which doesn't make a whole lot of difference to me, but YMMV (of course).
FWIW, I don't believe your Spanish Mauser (M93) to be appropriate for the 6.5x55, since it's use would require the bolt face be opened up/enlarged for the larger rim (larger than the 7x57), and "might" also need feeding work on the magazine throat area of the action underrails (again, due to the different case shape.
OTOH, if you can obtain a 94/96/38 Mauser (Swedish Mausers), you'd be Golden, since the bolt face & throat were made for the 6.5x55.
Last edited by PetahW; February 20, 2013 at 12:32 PM.