The Hastings "Wad Lock" barrels used a series of small Straight rifling grooves that were supposedly effective in stopping the wad from spinning, therefore increasing the effectiveness of the pattern. I knew a couple of guys who had them, and liked them. I cannot attest to wheter or not the idea worked as advertised, since I never owned one. At any rate Hastings made a good product. Sad to see them out of buisness now.