The velocity lost from 20" to 26" is minimal. I have a savage .308 with a 20" barrel that shoots 150grain bullets at 2950fps. How fast would they go out of a 26" barrel? Maybe, and this is a huge maybe, 3100fps. A more likely number is 3025. Why? Because the .308 has a finite ammount of powder capacity and it's actually rather small. If we were talking about a .300 win mag I'd say the 26" barrel would actually get you more velocity because of the increased powder capacity and the ability to shoot slower burning powders. .308 generally shoots powders with moderate burn rates. From my experimentation going much over 22" doesn't gain much velocity if any at all. The SPS tactical is a proven shooter and one of the most accurate out fo the box rifles on the market today. I know several people that shoot .3" groups and under at 100 yards with handloads and they haven't changed the gun. All they have done is work up custom loads tuned to the gun. However, if you feel driven to purchase a gun with a 26" barrel then go for it.