I have a Sig 556 SCM that I'm finally getting around to wanting to replace the default A2 stock. I see that I need an adapter for this, and obviously Sig no longer sells them. The ones on DDLES are out of stock as well. Looking to buy an adapter that will fit my Sig so I can replace the stock with something aftermarket. I live in MA so I need fixed/pinned stock options. If the stock adapter folds, I need to be able to pin/lock it and then add a fixed stock to it. Appreciate any feedback on this.