There technically shouldn’t be a turn line if I’m not mistaken. When the cylinder turns or indexes the cylinder stop picks up between the notches on the cylinder (not rubbing along the cylinder surface). The cylinder stop should then fall somewhere on the leading edge of the cylinder notch. In a perfect world there won’t be a turn line. I think the turn line is mostly caused by shutting the cylinder closed and spinning the cylinder until it locks in. Others will chime in with way more knowledge.