Luth-AR CS-02 Carbine Lock Ring/Castle Nut Black Steel - AR-15

The Luth-AR CS-02 is a carbine lock ring / castle nut designed to retain the carbine buffer tube to the lower receiver on AR-15 platform rifles. Machined from durable 4140 steel with a manganese phosphate finish, this threaded steel ring is built to withstand the rigors of regular use and serves as a critical structural component of any carbine build.

The CS-02 works with commercial, military, and M4 buffer tube specifications, making it a versatile replacement or upgrade castle nut for a wide range of carbine lowers. The black manganese phosphate coating provides corrosion resistance and a low-glare finish that blends with the rest of your rifle's components.

Whether you're completing a new build, replacing a damaged castle nut, or keeping a spare in your armorer's kit, the Luth-AR CS-02 Carbine Lock Ring / Castle Nut is an essential and economical part of your carbine rifle.