I have a Sb-1 receiver that I had sold the 12 Mod barrel. None of my other shotgun barrels would lock up on it. I had thought about selling it and it had layed in the gun safe for a long time. Last week I picked it up and tried the Versa-Pack 22LR barrel and behold it locked up fine. I had used this barrel on several different receivers, both Sb-1 and Sb-2. It has always shot pretty good. I mounted it on this Sb-1 receiver, put a Bushnell Sharp Shooter scope on it and headed for the range. After a few rounds at 25 yards of putting everything in less than an inch. (This is good for me because I can't shoot) I decided to try a round or two at 50 yards. I am still right in the center of one inch.... Again, I was impressed with the rifle and my shooting. As I took down the target, I decided to try one shot at 100 Yards..... I walked the 100 yards, put up a target, walked the 100 yards back and fired one shot..... LESS than one inch LOW. I took my target and my rifle and went home....Just quit while I am ahead.....