The .338 RUM would likely be just fine in a 24 inch tube.

There isn't a whole lot of difference in the case capacity to bore ratio between the .338 RUM or a .300 Winchester , and no seems to think it's an absolute neccesity to have a longer than 24 inch tube with the Winchester cartridge.....

The .338 RUM has a shorter case than the other RUM s and somewhat less case cpacity .

What they said. Go with the 26'' barrel. if u choose somthin shorter with all that powder burning u could bbq a buffalo from 20 yards away with that muzzle blast and light an aditorium on a dark night. just my opinion