www.gmriflebarrel.com should get you to the Green Mountain Barrel Company and they also sell the williams fire sites. They have drop in barrels for the Renegade and Hawkins. There are a lot of things to look at in their catalog. They used to and I think still do make the barrels that you find on the Knight Muzzleloaders. As this board will tell you, Knight in-lines are great shooting rifles.