Meaning of hollow-forge

hol•low-forge

Pronunciation: (hol'ō-fôrj', -fōrj'), [key]
— -forged, -forg•ing.
  1. to produce (a tube or vessel) by trepanning a hole in a forging and expanding it with further forging on a mandrel.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.