When Grey Birch Solutions designed their 10/22A(R) pattern bolt assembly, they did so with three objectives. The first was to tighten and control head space to .002, which significantly improves accuracy and consistency of accuracy. The second was to improve the external coating, resulting in increased reliability and extended bolt life by resisting corrosion. And last but not least, making assembly and disassembly easier. Bolt Material: Steel Finish: Polished Nitride Firing Pin: 17-4 PH Spring and Rod: 17-4 PH Assembly includes bolt with firing pin, charging handle, return rod, and return rod spring. *Compatible with most 10/22A(R) pattern receivers Mfg: Grey Birch Solutions