I have a Aea Hp ss . When I try to fill with my compressor the air leaks out the barrel and. It makes a weird vibration noise ?? It will hold air until I try to add my magazine
Yes sounds like the pin valve. It could be dirty or possibly broken. As others have stated, if it’s cocked and takes air, then hammer pressure is holding the valve open.
Think simply first, can you tear it down and put it back together? If so then begin to tear it down safely REMOVE ALL AIR. It could be as simple as an O-ring behind the tank and up in the receiver aera.
If it's vibrating and leaking out the barrel your poppet valve has broken. Empty your tank and remove it. Above tank inlet there is a large plug with a slot. Remove that. Your poppet is inside.