I have seen break-open shotguns equipped with "release triggers". The gun does not fire when you pull the trigger, it just clicks. It fires when you release the trigger. If you visit a trap club and see pellet divots all over the front of a trap house they were probably put there by a shooter trying to learn how to use his new release trigger. Once you pull the trigger the only way to keep the gun from firing is to break open the action while holding the trigger back. You can release the trigger once the gun is open and then unload the chamber(s). I find it a completely unnatural and only borderline-safe action and I prefer not to shoot in a squad including someone using a release trigger.

I'm told the purpose of a release trigger is to help someone overcome a flinch. Flinching is a symptom of having a fear of recoil and it causes you to jerk just as you pull the trigger, usually hard enough to make you miss. Supposedly, if you have already pulled the trigger when you decide to shoot, the action of just letting go of the trigger doesn't cause a flinch.