dip the end into a acetone and it will soften it up to streatch over then when the acetone evaporates of it will go back to its original state. this method works good for car cooling hoses and the like but doesn't work with chemical proof hoses so clamp the hose in a vice leaving barb length + 1/2inch or so sticking out hold the fitting with some multi grips to save the fingers and flog it with some timber or a rubber mallat. when you go to do the thread joint it will turn in the hose and put the clamp on after.