I have a FX Boss .30cal, and I am not impressed with the smooth twist barrel on it. From talking to continuum owners on this forum, who were kind enough to take measurements of the end of their barrel that slides into the action/receiver, I have found out that there is enough meat there to have it machined down to fit my Boss. If this works (BIG IF), I'll try the other calibers. Just imagine a NSA .177 or .22 slug being pushed out of something intended for a .30cal, but first I need to find a continuum .30cal barrel assy to experiment with.