I had a built in gun cabinet in my last house. My walk in closet had clothes in a L shaped arrangement. On the wall without clothes, I cut through the drywall so the cabinet would only stick out about half as far. Sides were screwed to the studs. I think I took out one stud so it was about 32 inches wide. I mounted a piece of 1.5 inch thick construction lumber at the right height for the guns to lean against. I laid them out along this, getting them about as close as possible, then traced the butts on a piece of 3/4 plywood. I cut out the shape of the butts and let the gun butts rest on the carpet through the plywood. Up top, I screwed pieces of softwood sticking out towards you into the 2X back rail to keep the guns from sliding to the side. Above the space for the long guns I had shelves for ammo and other things. The whole cabinet locked. It would not have been real hard to break into but my guns are not expensive. I mainly wanted to keep the kids out of them. Plenty strong for that.