How to Reduce Buffer on an AR15

Remove the magazine and pull the charging handle to the rear. Inspect the chamber to ensure there is no live round in the chamber.

Push the rear takedown pin from the left side toward the right.

Push down on the front of the barrel while holding the buttstock. The upper receiver will pivot on the front takedown pin.

Use the flat blade screwdriver to push down on the spring-loaded buffer retainer pin. Remove the buffer and buffer spring by pulling it out of the buffer tube. Push down on the buffer retaining pin as necessary, as the spring's coils may get caught on it.

Separate the buffer from the buffer spring.

Install the new buffer into the buffer spring. The pointed or rounded end points to the rear. The flat, circular end points forward.

Install the spring and buffer assembly in to the buffer tube. Push down the buffer retaining pin as necessary. When the buffer and spring are all the way in, let go of the retaining pin so it pops up. The front (circular) flange of the buffer must sit behind (to the rear) of the retaining pin.

Assemble the rifle, and then push the rear takedown pin in place. Pull back on the charging handle several times to check that the spring pushes the bolt forward. If the bolt does not go into battery (fully close), remove the spring and buffer assembly and check for obstructions. Also, check that the buffer retaining pin is intact and has not sheared off.