I've onyl had experience with the chrony models, but i've never had any problems. From arrows out of a longbow and slingshots to high powered wildcats, it'll handle them all. Oh, and you're measuring muzzle velocity with a shotgun. Unless you're shooting soem kind of ancient blunderbuss, you're pattern's not going to open up to a foot in the 14 inches it takes to go over the chrony.