I'm not really sure barrel length is that big of an issue with rifles, although I have found with pistols that faster powders tend to do better with the snub-nosed barrels.

With that in mind, powders like Win 748, Hod BL-C(2), or even Ramshot TAC are on the faster end of the spectrum for good .308 loads. 4895 and 4064 are perenial favorites for .308 as well, and Varget is gaining a good following as is Reloader 15.

In a bolt gun, you have a lot more powder options than the semi-autos do, so just about any powder on the burn scale from 748 to Reloader 15 will work...................it's just a matter of finding the best for you.