For a short time I had a full-stock mannlicher (no 10.xxx, Steyr AG) in 6,5x54 MS. I only shot five pieces of game (damwild, = small framed deer w/about 80 pds weight); I for myself felt, that that cartridge didn´t kill as well as a .243 but maybe it does better on other game.....
The other problem I had to fix was the rifling-diameter that measured .267 (instead of the usual-should-be .264). I solved it by using special ordered bullets in .267....
It was an sentimental experience (very fine technical solutions built in that rifle) though I do not feel the need to have another one 6,5x54....