That's interesting. The 220 Swift has a 'working' pressure limit of 62,000psi and the .270's is 65,000psi, both much higher than the more 'normal' MS ctgs.

My swift was fun, but after a re-chamber to .220 Swift IMP did not increase performance, I cut the barrel back and played with a .220 Short Swift of 1.6".(the original .22PPC)