I just fitted a Choate folding stock to my SKS-D.
The word "fitted" is used loosely ...
The instructions that come with the Choate folder mention that DOZENS of armouries built the SKS, and dimensions vary from gun to gun. With my SKS-D action, the Choate stock opening is so long, that the front comes out of the barrel fitting when the back is tight.
Choate provides a little piece of plastic to put behind the rear of the receiver, to shim out this space, but 40 rds at the range shows that recoil beats out the stock and the reciver slides forward enough that the whole disgusting mess comes vomiting out.
To fix this, I will be dropping in a 3/16" fitted aluminum lug, which will bear between the front of the receiver, and the cutout in the stock. This will keep the action from sliding forward.
NOTE: this is NOT a recoil lug ... it is the exact oposite, placed at the FRONT of the receiver, to keep the action tight to the rear, and prevent it from sliding FORWARD!!.