The CMMG Carbine Buffer Spring (brand part no. 55CA9A2) is a replacement action spring built for AR-15 carbine-length buffer tubes. Once the bolt carrier group cycles rearward on firing, this spring is what drives it back into battery and chambers the next round, so a worn or fatigued spring can show up as sluggish cycling or failures to fully return to battery. Swapping in a fresh CMMG spring restores consistent spring pressure and reliable cycling without replacing the whole buffer assembly. It’s sized for standard mil-spec carbine buffer tubes, making it a straightforward maintenance part for any AR-15 carbine build.

Key Specifications

• Buffer spring product type is a direct replacement for the AR-15’s action spring.
• Carbine-length fit is sized for mil-spec carbine buffer tubes rather than rifle-length tubes.
• Returns the bolt carrier group to battery after each shot to chamber the next round.
• 0.14 lb shipping weight confirms this ships as a small maintenance part.

Frequently Asked Questions

What does a buffer spring do? It drives the bolt carrier group back into battery after each shot.

What buffer tube does this fit? Standard mil-spec AR-15 carbine-length buffer tubes.

Buy the CMMG Carbine Buffer Spring, AR-15

Restore reliable cycling with this CMMG spring from our AR buffer system selection. Order it from our Lubbock, Texas gun shop for fast, direct shipping right to your door.