Here...
Check if there is some sort of protrusion around this area on your Glock and file it away. It's located on the left rail of the slide. If there is, file it away. My slide had this and it was the source of all my problems.
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Are you sure you seated the packing right? It should be neatly tucked away into the hop up casing.
The reason I say to make sure that the barrel is not tilting when the slide is in battery is because when the barrel tilts, it slightly pushes the hop up down. There is very little room of play even though the hop up unit is stationary but it can still move around.
If the outer barrel tilts up, it can take the inner barrel along with it and can cause the misalignment between the bucking and nozzle. It's like a seesaw-ing effect.