Hop-up/dust cover question.
 

I have a SRC gen. III pro HK416, and my dust cover doesn't come all the way back to uncover the hop-up knob when I pull the charging handle, Is this a common problem or is it just me? I can still adjust the hop-up so it's not a huge problem for me. just wondering.

How far does it come back? They don't come back far, maybe an inch and a half. Other than that the rest of the space is taken up by the front of the mechbox.