I put an ATI Draganov on my SkS-D and the stopers on the side were about 3/16's short so the rifle was moving that much in there. What I did was to figure out where that square metal bar that was built in the original stock was in relation to the body of the stock and put a similar device in my Draganov stock. I managed to measure perfectly and with the new stoper in place, the rifle feels and shoots marvelous.
What I used was one of those inch and a half long nuts from Home Depo and two flat screws. I measured and marked where the wholes where going to be, drilled and countersinked the hole so that the screw heads would be flash with the stock and then I screw them both into the long nut.
The nut having all those flat surfaces acts as the square bar in the original stock. I am very pleased with the results.
If you need more details, I could take pictures and email them to you. Too bad we can't up load pictures here.