I am no expert .. however you have to check if both the swing weight of both sets are the same ... if they are not the same .. it explains the reason of you able to swing faster with your friend's irons... For me I used to be using a set of irons that is weighted at D7 swing weight .. after I had changed my irons to a D1 swing weight I am able to swing much faster and ease ... however that also cause me to have other problems too ..