Ammunition Storage Components Magazine, 308 Win, Fits AR Rifles, 20Rd, Stainless, Black 20-308-SS-BM-B-ASC Ammunition Storage Components (ASC) builds some of the best magazines available on the market today. ASC magazines are built with the highest quality components to ensure reliable functioning and increased longevity. This is why they have become the approved supplier for many of the most well-known firearms manufacturers in the nation.