Yes, the tolerances are stacked. In order to get this to work with so many guns, sometimes a barrel "or anything else" can work in one gun, and not in another, simply put, the machining is off a degree in the same spot as other parts in the gun that are also stacked too far one way causing this to happen. A good gunsmith might be able to Mice the parts casing this and just mill a little off one spot. But I would return it and try another, which may work perfectly, or be the same, it's too bad you can't try like a dozen of them until you got one that had the tolerances in your favor.