single barrel vs system?

[MeteorGoliath]

What is the difference between a single barrel and a system in performance?

[CoolT]

With a barrel kit you can make sure you get a good paint to barrel match meaning better accuracy with multiple paint bore sizes. In a closed bolt gun it also insures the ball doesn't roll out the barrel. If the bore sizes match, a kit isn't going to have much or any better performance than a "non-kit" barrel.