One bit of cautionary information concerning a magazine fed .220 Swift in a short actioned rifle. The only magazine fed Swift I have seen was a Ruger a friend owned. It was very accurate, but the magazine box was too short for him to put more than one cartridge in it, when the bullets were seated out for enough to deliver the best accuracy with the 55 grain Nosler Bt's he was using. It's been long enough ago that I can't recall if it was possible to lengthen the magazine box, as I had to do with my Ruger .22-250. But I don't believe it could be done, at least not as easily as I did with my .22-250. With my .22-250 Ruger I just removed the baffle and installed a plastic one further back in the magazine box to permit loading and feeding of the slightly longer cartridges (about 1/10" longer, if I remember correctly).
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"Sir, I never take a chance when shooting waterfowl...
I believe in hitting him very hard with big shot from a big gun....."
-Nash Buckingham