zr2paul

Listen to what Mac said. Unless your gunsmith is an expert and experienced in Sidelock O/U, and has done work on the make you have, then you are risking much by letting him screw with it.

There are many fine gunsmiths that sell rifles for thousands of dollars that will not touch a quality sidelock. It is because it is it's own world and can be extremely complicated.

It can happen that shooters occasionally bump the rear trigger. That is the first place to check. If it is an ejector that will also spring when the second barrel fires.