A method and apparatus are disclosed for substituting a different forend assembly in a long gun (e.g., a shotgun) without the use of tools by a user in the field. Applicants' preferred apparatus for substituting a forend comprises: a modified forend carrier that is affixed to the long gun (e.g., the illustrated shotgun); a forend; and tool-less means for removably attaching the forend onto the carrier, or removing the forend off the carrier, without the use of tools, wherein the tool-less means comprises: (i) a tongue-and-groove arrangement in the forend and carrier, and (ii) a releasable lock contained, at least in part, in the carrier. This permits the forend to be swapped out.