Several companies make hand operated tools to crown rifle barrels. Most use pilots to align the crown at right angles to the bore. Brownnells sells a couple of different brands. If you have access to a lathe it is a simple task. I usually just use the hand tools as it so much quicker and amply precise. The tooling is quite pricey for just one cut off. It may be financially better to simply let a smith handle it. There are quick and dirty ways to accomplish the deed but they are more for the emergency than because they are so good.
