MemberAugust 28, 2020 at 2:50 pm13 Bullseyes
In a recent (fall/winter 2019) issue of Guns & Ammo Precision Rifle Shooter, editor Patrick Sweeney did a real-world velocity vs barrel length test with the 6.5 CM, by cutting off the barrel on a Model 700 Remington, 1″ each series of shots, and recording muzzle velocities. He used 6 different premium factory loads, starting with 24″ of barrel and ending with 7″, one inch at a time (and many sawzall blades later). Fun article, if you can find it online!
His results using lighter hunting loads (125-gr to 135-gr) showed an average decrease of just over ~100 fps between the 24″ and 20″ barrels, while heavier target ELD loads (140-gr to 147-gr) averaged ~80 fps difference.
When shooting targets or steel beyond ~300 yards, I want every fps my bullet can muster, meaning a longer barrel (SD & ED being equal). I am not a PRS competitor, but most of those guys shoot 26″ barrels (not for accuracy, but for velocity).