The Spike's Tactical Carbine Buffer Spring is a Mil-Spec 17-7 stainless steel buffer spring that features an electro polish finish to give it a smoother quality look and feel.This is the same high quality carbine buffer spring that's found in our complete rifles, complete lowers, and in our various stock kits that we have on the site. It's a Mil-Spec 17-7 stainless steel buffer spring that features an electro polish finish to give it a smoother quality look and feel. If you need a replacement buffer spring or just need one to finish a build, look no further. Get one today.