Introducing the Dirty Bird AR-15 17-7 Stainless Steel Flat Wire Spring. Buffer springs are often a part that is overlooked when building an AR from the ground up, but a quality buffer spring can prevent “stove-pipes”, misfeeds, and ensure popular cycling. The Dirty Bird Flat Wire Spring will have your AR running at optimum performance and outlasting a standard music wire carbine buffer spring. Constructed from 17-7 Stainless Steel, this buffer spring is crafted for extra abuse and maximum toughness. Finally, a coating of Sandstrom 28A is applied to the spring. What is Sandstrom 28A?