Rice Barrels, and the Oregon Barrel Co. Both make 'Drop In' Fast twist barrels, As far as Complete Rifles go, Lyman and Pedersoli are the only currently produced fast twist rifles i know of? Pedersoli makes a few different Fast twist rifles. The only brand new bought Muzzleloader i own is a Lyman Great Plains Hunter .54 Cal 1:32 Twist. I hated that thing at first, but after some modifications to suit me I actually really like the rifle now, It shoots REALLY good, and is not at all finicky. I have shot several different length-weight ranges of bullets through it and so far it has shot everything I've tried in it really well. The Riflings are REALLY sharp in this rifle!!! I polished the absolute daylights out of the bore with Montana Extreme Bore polishing compound before i ever shot it the first time, I've never seen riflings this sharp? It actually scars my Jag when i patch through it, but doesn't have any effect on accuracy