I had a Knight project a while back. I was trying to get a fire damaged gun back in use. I was able to easily get the barrel & a few other parts from Knight. I know they closed but someone took over the repair for them, they should have some barrels available. I would think gunbroker & others shold also have some parts.
There is a company covering some warranty work for them. They have a recall right now on a different gun than yours. The number to call for Knight rifle warranty work is 1 800 696-1703. I think they are in Alabama. I'd call them & see what thay have to say.