The way the Stop&Go concept works is that after each shot, the bolt cycles back (extracts, ejects, cocks the hammer) and gets caught in its rearmost position. Imagine a bolt hold open mechanism catching the bolt not only when the magazine is empty, but after each and every round fired. After each shot, the shooter has to manually release the bolt using the large thumb actuated lever. So it is a gas operated shotgun, but it only cycles the mechanism halfway.
Why would they need to design such a useless feature? The answer is because of legislation. It is reportedly designed to comply with the restrictive European legislation. Like in the case of featureless AR-15 stocks/grips, bullet buttons and many other ridiculous guns and parts, the designers just had to find a way to comply with the law.
Among other features of Verney-Carron Veloce are the walnut stock, rubber butt pad and 710mm (28″) barrel.
Here is a video by Verney-Carron showing the Veloce shotgun:
So this is like a half semi-auto half manual/repeating action!? It does have a semi-auto mechanism but interrupts the action right after ejection. What do you think is the proper name for such an action?
UPDATE: According to the patents owned by Verney Carron, the action is referred to as an ‘assisted linear’ action.