trigger guard installation
They are not easy to re-install. I do not know what double action you have but they are pretty much the same. The "V", closed portion, end of the spring sits toward the front of the gun. I would fit the trigger guard first, then place the spring on the guard and move it in place. Be aware, the front sits on a tab and must stay in place while you force the trigger guard to the forward position. Sometimes, I good blow, with a plastic or hardwood mallet will seat the trigger guard while you are holding pressure on the trigger guard to give it that extra force to secure the guard on the gun. You can order David Chicoine book on antique forearms assembly/disassembly for step by step instruction on these type of tip-ups, top breaks and the other antique firearms for disassembly.
Nick