After you insert the new buffer in the spring, carefully guide the assembled pieces into the buffer tube. (Photo: Guy Sagi)

There are a variety of reasons to gain access to an AR’s buffer and buffer spring ranging all the way from routine maintenance to installing a high-tech version that silences the metallic “sproing” every time the gun is charged. Some claim changing to an H- or H2-weight buffer even reduces perceived recoil.

Getting to the assembly isn’t...