I have just purchased 2 Savage rifles in .308 Caliber. One is a Model 10 FP with a 24" barrel, and the other is a 12F/TR with the 30" Stainless barrel. With all things equal ammunition wise, what velocity difference will the extra 6" of tube make? I can't find anything in any of my manuals that show 30" barrel velocity data. Has anyone run any real world chronograph tests? Thanks in advance, Bill T.