You are talking about the French made "Darne" shotguns. The retraction of the breech block, ejection of the fired shell and reloading of the new round is all done by pulling back on the trigger guard. Works like a pump action but instead of using the forearm to cycle the action, the trigger guard and related breech parts are pulled backwards each time to do the same thing. It seems awkward at first but it actually works pretty good when you get used to it. The Darne are quality guns, not cheap.