Maintaining machinery to keep tolerances within certain limits requires replacing worn parts at specified intervals. This is expensive, and so is culling rejected products. Once I sent back to Olin a high dollar but defective double shotgun. Olin replaced it. The head man told me they destroyed the one I returned. He added that they had also destroyed a large number of double rifles that failed to meet standards. After cutting them up, they ceased selling double rifles. Few manufacturers can afford this QC standard. Those shipping defective firearms probably know the score but ship duds anyway.