Browning A5 shotgun bolt locked with spent shell

Hunting guide recommended putting spent shell in chamber to "protect firing pin". Three weeks later I find I cannot get the spent shell out. (I've had the gun since 1965 without any problems so stupid me for listening to the guide.) I push the release button but can't pull bolt back. Can anyone offer any help or do I need to visit a gunsmith? Thanks.

I get to answer my own question with a simple answer. I took the A5 to a gunsmith. He set barrel bore directly on floor and pushed down on the gun stock. Then he was able to pull the operating handle to eject the spent shell. The A5 depends on a discharge to eject a shell. Since the trigger had been pulled on the spent shell it could not be ejected the normal way - very logical!