I dont see anything about a proprietary chamber in knights info on their site. Are you talking about the round lug bolt? and if it requires a specific extension on the barrel?
If so from my limited research, the e3 bolt is specific to the bolt extension, which is not easily remove able from the barrel.
Are you changing barrels just to have something different or is your barrel shot out? If its just for something different, id suggest getting a new bolt to go with the standard extension your new barrel will have, and keep your old bolt with its barrel.