An IEC with grip

I am sure this has been discussed ad nauseum, but I have not found what I am looking for yet. I have built several power cables and bought a bunch, but I am consistently disappointed by the IEC plugs and their weak grip. I have spent some bucks on Neotech and Wireworld plugs and cords, and they frequently have to be pushed back in place. One of the cords that does have grip is the Classic+ that I received with my Puritan PSM156, that holds quite well. 

Any suggestions? I know that I can improve things by wrapping the plug in tape to make it stay put, but my interest here is finding something with grip that will improve the connection.