A&K hop-up - new bucking needed?
 

I'm running a stock hop-up system on a A&K SR15.

Currently, it has zero hop up. When I crank the hop up all the way up, the gun double feeds constantly.

I've taken the hop up / barrel assembly out and made sure everything is lined up. It all looks okay. When I turn it up, the nub does start to form through the window on the barrel, where the bucking nub is.

First time dealing with this problem. Any input appreciated.

I replaced the hop up nub, under the bucking, with a small square of eraser to the same effect.