[yanhchan]

So when I look down the back of my barrel of my newly installed madbull hop up it looks a bit lopsided to the right. Anyone else had this problem. I think it is due to the three "shark teeth" that they used to prevent double feeding. If I followed the groove to match my barrel everything should be ok right?

Also the X shaped hard piece of rubber won't go in so I used my old rubber instead. would this affect the gun's performance dramatically?

I installed the hop up onto my TM M4 stock hop up unit.