The 336 series have 1:10" twist Microgroove® Barrels (12 Lands & Grooves); the XLR 30/30 rifle has a 1:12" twist with Ballard Rifling (6 Lands & Grooves). The XLR has a ⅔ Magazine in all calibers while the 336 series has a full length magazine tube. Additionally the XLRs has a much smother action, crisper triggers, (IMHO) a fluted bolt, and a fine Pachmayr® Decelerator recoil pad.