Dave- although it is tough to diagnose these things remotely, there are a limited number of things that would prevent your toplever from snapping back on these barrels (presuming they function properly on the original set). I suspicions (as Ho'ace Miller was wont to say...) that the bolt is hanging up on the wear plate (mostly likely the angle of the plate is just a hair shallow. As one can not mess with the bolt on a 2 barrel set, a little engineers blue (or magic marker) on the plate might show you the spot and a stroke or two with a stone might make it work normally. Ideally, you could fix this easily and still complain about in retrospect..a win/win situation for you...
