Asking $275 obo, I am in the Placerville area, so if your nearby we can meet FTF, if not I can ship buyer pays shipping.
Here is the description from Midway.
The Adams Arms gas piston conversion is a complete retrofitting kit that brings a standard AR-15 rifle into the 21st century by replacing its dirty direct gas impingement operating system with a cooler, cleaner, short-stroke gas piston design. With the piston conversion installed, hot combustion gases are kept out of the upper receiver and vented forward, resulting in a gun that remains cleaner and cooler during operation for increased reliability and decreased maintenance.
The gas piston kit installs easily, requiring no permanent alterations to the rifle, and adds virtually no additional weight to the gun. The kit comes complete with a replacement gas block (with integral single Picatinny top rail), piston and piston return spring, operating rod, solid steel one piece replacement bolt carrier , handguard cap, properly relieved M-4 style handguards, installation hardware and complete instructions. The low profile of the Adams Arms piston design makes it compatible with some free-floating handguards, however removal of some material from the upper portion of the free-float handguard may be required for use with this operating system.
- Gas block
- Piston return spring
- Operating rod
- Handguard cap
- Upper Receiver Bushing
- Installation hardware
- One piece bolt carrier
- The one piece bolt carrier features an integrally machined, solid steel strike face to absorb the operating rod's energy, as opposed to the modified bolt carrier key provided with the kit that uses the traditional screw attachment method to retrofit a standard AR-15 bolt carrier.