The collet bushings were supposed to improve accuracy by tightening up around the barrel when the pistol was in battery. The problem was not with the design itself but Colt's quality control. If the slide ID was too small the fingers of the bushing would buckle under the pressure and eventually break. Also if the front of the slide wasn't machined perfectly square it would stress the bushing as well. But as long as the slide was machined to proper specs the bushing usually worked fine and lasted a long time. National Match barrels usually have a narrow chamber hood dimension so I don't know what you've actually got in that pistol. Have him take pictures of the ejection port with the barrel installed and see if there is a large gap on the side of the hood. If there is then Colt didn't install that barrel.