M4 Charging handle

[Ouzx]

I've just received my new M4 today and the charging handle to reveal the hop up is sticking and I have to slam it back for it to reveal and for the dust cover to actually open. An I'm not sure if it's the design but the hop up cover, not the dust cover is stuck in it's place when I thought it pulls back as the charging handle is pulled back and usually you must hold it in it's place when adjusting the hop up but it's on show with no cover if that makes sense so I'm not sure what to do. Remember I'm fairly new to this and these sorts of problems.

 

[RR01]

Some do that, others don't. It will be the false cylinder not sliding cleanly in the grooves on the inside of the upper receiver. Try a squirt of silicon oil in there to see if that helps it, but don't get any in the hop unit.