Anyone here into firearms?

Originally Posted by SouthArk370Z

A buddy of mine has a Mossberg 500A 12ga pump that had been sitting in the back of a closet for a long time and collected a lot of dust plus some surface rust. We decided to break it down and give it a good cleaning. The barrel wouldn't come out of the receiver. Looked at a few videos on Youtube and they all show the barrel almost falling out once the magazine bolt is unscrewed. Sprayed the barrel/receiver joint with WD-40 and let it sit overnight but it's still stuck. Any suggestions? Is the chamber steel hard enough that I can use a brass rod to knock it out from inside the receiver?