I think that you might be amazed at the velocity of a 26" 270.
You can always cut it off later, you can never put it back on.
Buddy of mine built a #5 contour, hart barrel, 29" long some years back for shooting chucks at long distances(he like to see them get airborn). I can't remember the numbers, but the velocity was like nothing I had ever read about clocking it across my Ohler 35P. What I do remember was that it was stomping hell out of a 257 Weatherby's velocity.
