Here is what I think Jack was saying:
To measure choke constriction on a barrel you don't need to calibrate the dial bore gauge with the calibration ring. From the muzzle end insert the dial bore gauge a few inches. Set the dial indicator to zero. Move the bore guage out to where the balls are at the muzzle. The dial indicator reads directly the amount of constriction in that barrel in thousandths so there is no math.
Using this method you don't know the bore diameter nor do you know the diameter of the muzzle. But you do know the constriction. You do not have to use the calibration ring.
Best,
Mike
Mike, I think we all got that. But where Jack fell off the wagon was with the brass drop-in gauge--because everything it tells you is based on the assumption that the tool itself knows the bore diameter. Which it does, but only IF the bore diameter is standard. Which is a big IF.
