It's been my understanding that Remington barrels, such as those on the 870 and 1100 are/were cold hammer forged. From Remington's website:
"5) Are all Remington barrels hammer forged?
No. Most of our production rifles and shotgun barrels are hammer forged, though we do use various barrel manufacturing techniques to suit the unique needs of various weapons and systems.
6) Does Remington make all of its own barrels?
No. While most of our barrels are made in-house on our state-of-the-art cold hammer forging equipment, we do source barrels from various industry leaders based on the requirements of our customers."
