AR-15 Buffer Retainer Spring

Buffer Retainer Spring

This is the small coil spring that sits under the buffer retainer in an AR-15 lower receiver. The buffer retainer is the little pin that pops up to stop the buffer and action spring from shooting out of the buffer tube when you open the upper. If that spring goes missing during a build or a teardown, the buffer has nothing holding it in place. This United Defense spring is a direct replacement and a cheap spare to keep in the parts bin.

Features

• Buffer Retainer Spring — Pushes the retainer pin upward so it catches the buffer and keeps it in the receiver extension, the tube behind the lower that houses the buffer and action spring.
• Replacement Part — Swaps in for the original spring in a standard AR-15 lower when yours is lost, kinked or worn.
• Straight Coil Design — A single compact coil spring, as shown, that drops into its bore in the lower receiver.
• Copper-Toned Finish — The spring has the copper-colored finish visible in the photo.
• Spring Only — The listing covers the spring alone, and the buffer retainer pin is a separate part.
• Useful Spare — Small springs are easy to lose during lower assembly, so having one on hand saves a build from stalling.
• United Defense Brand — Made by United Defense, a commercial parts maker rather than military surplus.

Fit and Installation

The spring goes into the small hole just below the buffer tube threads on the lower receiver, with the retainer pin set on top of it. Threading the buffer tube in holds the retainer down against the spring. To replace it on an assembled rifle you will need to remove the buffer tube, which on a carbine-style stock means loosening the castle nut first.