i had a swift 6-18x50 (bought from Marty at Silver Streak Sports, no longer in business?) on a pro-elite .22 for 7 years now, that was when that Swift model was suggested by straightshooters as a medium recoil scope. i was wondering about their new Swift SRP sur-lok 669M-SL, but now after reading your review i have doubt in Swift. i read that their quality is no longer what it used to be.
an example of other people using the Swift 6-18x50 model on magnum springers is here, the pics of rws 48 setup for night hunting at the bottom.
http://airgunpower.homestead.com/pics.html