Tell ya what now that Kdog mentioned the barb . A long time ago, really long time ago, I clamped a pair of needle nose in a vise . Drilled the seam of the jaws from side to side making a hole all the way . then chamfered that hole an 1/8 inch on each side . That let me squeeze the barb down . I'd think with more pressure it would produce something of a collar as well .