Aero Precision M5 .308 Carbine Buffer Spring. 308 rifle buffer spring for use in .308 AR's with a fixed buttstock. Perfect for your new build or as a direct replacement for worn out parts. Note: Will not work with .308 carbines with a collapsible stock. Specifications for Aero Precision M5 .308 Buffer: Manufacturer: Aero Precision Color: Stainless Steel Gun Make: AR Platform Gun Model: M5 Condition: New Country of Origin: USA Caliber: .308 Winchester Package Contents: Aero Precision M5 .308 Buffer What firearm models does the manufacturer say Aero Precision M5 .308 Buffer is compatible with? The manufacturer says that Aero Precision M5 .308 Buffer is compatible with M5Aero Precision APRH100133C: M5 .308 Carbine Buffer Spring