I have the same issue when bareshafting. I have used a piece of peep tubing covered in velcro to raise the contact point of my shelf and also shoot with minimal pressure on my index finger(split grip). This has helped, but I still get nock high bareshafts. I do not find it a problem once I switch to fletched arrows though. I bareshafted some Bemans just yesterday from my Morrison recurve and though I got nock high, barely weak bareshaft results, the fletched arrows show perfect arrow flight(nothing but spinning ball of feathers).