A barrel liner is the rifled tube fastened into the bore of a barrel to replace the surface during barrel relining.

This is usually done to restore older guns with worn or corroded bores to shooting condition. It can also be done to change caliber (in certain instances) or to improve accuracy.ﾠThe basic process is to drill out existing rifling, soft solder or Acraglas the new liner in place, then cut a new chamber and muzzle crown.

aka:

• barrel sleeve (shotguns)

related:

• barrel relining (rifled barrels)
• barrel sleeving (shotguns)

 

Footnotes / Sources:

“Glossary ⇒.” Sporting Arms and Ammunition Manufacturers’ Institute. Ed. SAAMI’s Technical Committee. Web. 15-18 Jan. 2011.