Numerous issue can appear because of a badly built hop unit. It does a bit more in an AUG than just lift BB's. It also gives the spring tension that holds the body pin in.
Some things to look out for.
If the brass ring is visible through the 2 screw slots on the side of the unit it might mess up the rebuilding of the gun and mess up your air seal. The hop unit needs full travel on the slots. I always cut my bucking and put the brass ring in on the gearbox side of the C-clip to stop this happening. I don't think any of the videos online show this mod, but it helps rule out the ring and screws interfering with the hop movement. Others just put the ring right at the end of the hop unit making sure the screw slots are clear.
If the 2 screws are touching the inner barrel and stopping the hop unit moving freely they need backing off. Until the hop moves freely forwards and back in the mounting block. It should have 4-5mm of travel. And should spring fully back without resistance. Those screws do not secure anything they act like pins stopping the hop unit leaving the mount, They don't need to be fully tight to work. It's the spring back action that sets the body pin tightness!
The rear ring needs to be installed correctly and triple checked. It sets the airseal nozzle engagement distance from the gearbox. If it's not correctly seated you will get airleaks, and the BB's might not feed.
The C-clip needs to be installed so it's absolutely flush to the hop. If it's stuck up in any area it'll bind in the mount and stop the unit moving freely. You sometimes have to put a bit of compression onto the unit to get the clip to drop in snug. When it's right it's nice and tight usually, and holds itself in place.
You also need to check the bucking feed lips. Aug hops have a nasty habit of pinching them at the top. They also sometimes pinch the bucking at the back side of the hop window.
Numerous issue can appear because of a badly built hop unit. It does a bit more in an AUG than just lift BB's. It also gives the spring tension that holds the body pin in.
Some things to look out for.
If the brass ring is visible through the 2 screw slots on the side of the unit it might mess up the rebuilding of the gun and mess up your air seal. The hop unit needs full travel on the slots. I always cut my bucking and put the brass ring in on the gearbox side of the C-clip to stop this happening. I don't think any of the videos online show this mod, but it helps rule out the ring and screws interfering with the hop movement. Others just put the ring right at the end of the hop unit making sure the screw slots are clear.
If the 2 screws are touching the inner barrel and stopping the hop unit moving freely they need backing off. Until the hop moves freely forwards and back in the mounting block. It should have 4-5mm of travel. And should spring fully back without resistance. Those screws do not secure anything they act like pins stopping the hop unit leaving the mount, They don't need to be fully tight to work. It's the spring back action that sets the body pin tightness!
The rear ring needs to be installed correctly and triple checked. It sets the airseal nozzle engagement distance from the gearbox. If it's not correctly seated you will get airleaks, and the BB's might not feed.
The C-clip needs to be installed so it's absolutely flush to the hop. If it's stuck up in any area it'll bind in the mount and stop the unit moving freely. You sometimes have to put a bit of compression onto the unit to get the clip to drop in snug. When it's right it's nice and tight usually, and holds itself in place.
You also need to check the bucking feed lips. Aug hops have a nasty habit of pinching them at the top. They also sometimes pinch the bucking at the back side of the hop window.