Re: What would be the best way to close a barrel channel?
Put a layer of blue painters masking tape down the length of the barrel then cover that with a layer or two of duct tape(to your taste) on top of that. Then just bed it like you would an action. Once you remove the tape you should have a free floated barrel, if you have a tight spot you can sand it down.
Ignorance can be treated with education, sadly there is no cure for stupidity.