I would suggest you go and read Melissa Kaplan's article on hard feeders in the resource page of kingsnake.com to begin with. It covers just about all the options. Also are you trying frozen thawed or live pinks? Are you using a deli cup as far as the small space? If the little guy is as agressive as you indicate, he is probally getting so upset that food is the last thing on his mind.
Sometimes you have to think outside the box to get the job done, for instance I had a san deigo gopher last night when I was feeding that was really upset, striking, hissing the whole 9 yards and I could not get him to eat. I finally fed all the other animals and went into the house for a couple of hours and then slipped into the snake house In the dark and put a dead mouse in his cage. I checked him 30 minutes later and he had taken the mouse with no problem. A little comical with me slipping around in the dark to feed one silly gopher, but it worked.
I would also check my husbandry as far as temps, traffic around the cage etc. to get a handle on the agreesive behaviour.
John Cherry
Cherryville Farms

Cherryville Farms - Reptiles