Keith,
If you have any regular AK dust covers handy or can get your hands on one, it is possible to modify them with simple cuts to work with your S-12. I have numerous AKs, an S-20 and an S-12. I cut up a ribbed AK cover to work with my S-20 with a regular AK RSB and FSB. My S-12 I welded an RS onto the stock dust cover and FS on the gas block. I can interchange the dust covers for the shotguns AND the AKs but we all know that the shotguns won't cycle or eject with a regular AK cover so they have to be cut appropriately. Just copy the cut on your existing S-12 cover on a regular AK c