If the OP is still interested in a fast twist .220 Swift and hasn't got .220 Swift dies yet, a .220 Wilson Arrow might be a better alternative using the Swift case. Case stretching is greatly reduced because of the 30 degree shoulder, the marginally lower shoulder/neck junction plus a short-throated reamer would be better for the longer high bc 75 grain and up bullets so as to fit in the magazine. Case capacity and velocity is virtually identical.
