The Hilsabeck FLATLINE replaces the factory buffer spring inside of all rifles chambered for .223 or 5.56 in the carbine length buffer tube. The FLATLINE will significantly reduce muzzle lift to maintain sight picture, and place you on target faster. The FLATLINE kit comes with three springs allowing you to adjust performance to your need. Instructions included in the kit will explain the use for each spring.

*Does not fit the m16a1 model as the buffer tube is too long.*