try ehobby asia 
Now a 'namsofter. I have an M72 L.A.W. for sale for 110 posted, PM if interested.
You don't need to change the actual hop unit itself. Just fit a better hop rubber along with your choice of barrel. 
When I want your opinion - I'll tell you what it is!
it may be your hop rubber is really hard, just buy a hard rubber, and a soft one, and compare the differences, like sgtheide says, i think its unnecissary buying a whole new hop unit.
Now a 'namsofter. I have an M72 L.A.W. for sale for 110 posted, PM if interested.
Try a different type of hop bucking as well. I've found that a hard bucking/softer hop rubber combination can work quite well.
When I want your opinion - I'll tell you what it is!
I was having an issue where I have to turn the hop-up completely off in order to get the BBs to shoot straight.
Mine does that too. Doesn't it make the FPS better if the hop's not binding as much on the BB?
