LUTH AR 223 Carbine Buffer Spring

The LUTH-AR .223 Carbine Buffer Spring is a standard mil-spec action spring for AR-15 carbines. It installs in a carbine-length receiver extension behind the buffer, where it cycles the action and returns the bolt to battery.

This is a direct factory-style replacement. LUTH-AR lists it for .223 Remington and 5.56 NATO carbines that use an M4-type (carbine) receiver extension for a collapsible stock. A buffer spring is a normal wear item: over many rounds it can lose tension or develop a kink, which shows up as sluggish or rough cycling. Swapping in a fresh spring restores normal function.

This is a standard spring, not a centerless-ground or polished competition spring, so it will not change recoil feel or cycle noise the way a tuned spring does. For a reliable, low-cost replacement, it covers the job. Confirm your build uses a carbine-length receiver extension before ordering; rifle-length tubes use a longer spring.