The AR-15/M4 carbine buffer spring replacement part is made in the USA with a Limited Lifetime Warranty. This AR15 buffer spring upgrade is perfect for replacing worn or broken buffer springs and fits all commercial, military, and hybrid buffer tubes. Getting a new buffer spring will help ensure consistent, dependable operation of your AR rifle for thousands of compression cycles, and the rifle will cycle better and eject more positively if your old spring is worn or has lost tension.