Black Market appears to have them in stock.
http://blackmarketarms.com/product.century-arms-c308-semi-automatic-308-win-18-barrel-black-finish-pistol-grip-1-5rd-and-2-20rd-g3-magazines-2990
Looking for a Zenith (MKE) 5RS. If you have one minus the pistrol brace please PM me the cost.
Due to locating the pistol, I'm no longer in the market.