I have sqeeeezed 40 amp cable into a Dura plug. I suppose it will depend on the outer casing but my mains at the time was really soft rubber. I seem to remember cutting where the cable enters the plug. This was to facilitate my 2x13 amp into 63 amp plug adaptor. One of many adaptors out of a box that contained everything into everything else.
Peace and goodwill to all speaker builders
