ORIGINAL: MK-M-GOBL
Here's a short clip from Nitro Company's web sight. They make some of the turkey loads around and know theri stuff. Hope it helps
The modern turkey hunter sacrifices pattern performance and velocity for maneuverability of a short 21" barrel. A gun with a 26" barrel will give you higher velocity and better patterns. For every inch up to 26", you gain 7 1/2 to 15 feet per second in velocity, depending upon the gun. A 26" barrel will give you 10 to 15 percent better patterns than a short barrel with the same choke constriction.
I respect Nitro and everything, and they obviously have done their homework on their patterns, but every single ammo company and gun manufacturer disagrees with that statement. Remington, for example, says that with modern shotgun powders burning much faster, that a charge of shot has reached its maximum speed at 18-19" in a barrel. I know Nitro is a big name company with turkey hunters.... but I think Remington probably has a little bit more advanced testing systems... just a shot in the dark there.
There is a great article in the latest Turkey Call magazine about barrel length, and why it used to be that longer barrels shot tighter patterns and shot faster, and why that isn't so anymore. They spoke with 5 different companies I believe, and all of them said pretty much the same thing......