do a 3 stooges episode. Light a match, put it down into the vent hole and look down the barrel no, don't do that.

One way to see if it came out or not is to pull the barrel out of the stock and carefully pour some water down the bore. Or just attach the ball puller onto your ramrod and see if you can feel anything.

Hell even just puckering up and putting your mouth around the vent hole and blowing will confirm if it came out or not.