I am looking to re chamber a rifle to 220 swift or 220 Ackley improved. I have been told to try a 220 Swift Ackley improved with a 1 in 12 twist with a 28" barrel. What are some of the advantages and disadvantages of the 220 swift and or the 220 swift Ackley improved. What I'm looking for is a rifle to shoot a tight group any where from 200 to 600 yards for varmint hunting or target shooting. Most likely I'm going to be useing 50 to 60 gr. bullets seeing that I have 5 other rifles chambered in .224 cal.