Re: 220 SWIFT QUESTION
About a hundred more than a .22-250. Just remember that those original velocities were with a light 39 grain bullet. Before modern chronographs, may I add. Modern powders can boost what the original powders produced. Only real problem is the more severe taper of the cartridge case that allows more stretching and which requires more frequent trimming, shortening case life. Which is why the original Ackley Improved type chamber was devised. Care with neck sizing when you can, and a body die to only bump the shoulder as necessary will help. JMHO