Question for Beretta 391 shooters - bolt sticking

I have a 20 gauge 391 that recently the bolt has started sticking when closed. This is when I close the bolt on an unloaded gun. I need to tap the bolt handle kind of hard to get it to open. What might be the reason for this? Thanks in advance.
William

 

Have you tried to 'dry fire' it to see if that makes a difference ???

I would guess a trigger issue or the link behind the bolt that goes into the action spring.

 

Thank you. The link is fine and the dry firing makes no difference. I have tried 2 different triggers, same results. I appreciate your answers.
William

 

Take the forearm off so you can take the bolt handle out and work the action.

 

Time for a new recoil spring, remove the spring, clean the tube and look for dirt lodged under the part that the follower rides on