Actually, the .308 case is getting very dated. What we need for the next generation is a 6.5x47 Lapua necked-down to .25. Get Ruger to chamber it as the 257x47 77.
If you don't like that, how about the 6.5 Creedmore necked down? Call it the Quarter Creedmore.
KS
ETA: Added a smiley just in case.