The whole thing stems from a divorce. His ex told the cops he had weapons in the house. There was 1 or 2 warrantless searches and at one of these they found a muzzleloader. Kind of unclear on this, but he either wasn't charged or charges were dropped for this.
I believe the dud (primer struck, but did not fire) shotgun round was found during a later search with a warrant. He had kept it as a momento from a hunt and it was laying on his desk.
He was to appear in court again yesterday. Haven't heard the outcome of that.