On a 308, 24" is the longest you will ever need on an SWS. The factory ammo and Varget loads will get pretty much top velocity out of a 24" tube.
The Palma 1K guys shoot 155GR bullets with alot of slowish powder. That is why they use the long barrels, to burn all that slower powder.
We use 26" tubes on 300 Wins and27" tubes on 300 RUM and .338 Lapuas. Seems to get the job done pretty good without making the barrel so long it is worthless to deploy.
FWIW
Celt
The Palma 1K guys shoot 155GR bullets with alot of slowish powder. That is why they use the long barrels, to burn all that slower powder.
We use 26" tubes on 300 Wins and27" tubes on 300 RUM and .338 Lapuas. Seems to get the job done pretty good without making the barrel so long it is worthless to deploy.
FWIW
Celt