These brass cones take much of the anxiety out of lathe-turning a perfectly good barrel with an already finished crown. Insert a Crown Saver between the muzzle and lathe or mill center before fluting, chambering, polishing, or threading for a muzzle brake, and you can rest assured you won’t harm the rifling or ding the crown. Each brass cone is machined to within .0002" or less concentricity, making using a Crown Saver as accurate as direct barrel contact against the center. With a Crown Saver, you virtually eliminate any chance of swaging the rifling. It stays seated and will not spin in the bore when the barrel is chucked in the lathe. Small fits bores .17 to .45 caliber. Large fits bores up to .50 caliber. For best results, do not use Crown Saver more than once on barrels of the same caliber.