I've had too many issues with the .683 rifled barrel. It's just far too tight, forcing one you crank up the gun's operating pressure to the point where it's too brutal on the rounds. The velocity consistency when using the .683 rifled was just all over the place too. Windage that thing was dead on, but elivation wise it was the shots were quite inconsistent due to the velocity fluctuations. I found the stock smoothbore, flasc smoothbore, and the hammerhead .688 rifled much more reliable and consistent for FSR use.