If you ever need to take the barrel off, remove the retaining bolt/plate, retract the bolt and let it slam forward.
You'll need to "hammer" the bolt a few dozen times to drive the barrel out of the receiver.
Just FYI, the ejector(little metal strip that kicks the cases out) is staked to the barrel. Make sure you're holding the barrel as you pull it off or you'll end up bending the ejector.
Whatever you do, DO NOT attempt to twist the barrel out of the receiver.
@chalkriver - In my limited experience with these rifles, they only shoot accurately with very high velocity stuff. I've only had good results with Rem yellow jackets.