Cold Hammer Forged
Also: CHF · Hammer Forging
A barrel-making method in which powerful hammers forge the steel over a rifled mandrel, forming the bore and rifling in one fast, durable operation.
Cold hammer forging starts with an oversized blank drilled to accept a hardened mandrel that carries the reverse image of the bore and rifling. Banks of hammers then pound the outside of the blank, squeezing the steel down onto the mandrel so the chamber, bore, and grooves all take shape at once. The cold working densifies the surface and leaves a tough, work-hardened bore that resists wear.
The method is fast and repeatable, which is why it dominates factory and military production where thousands of identical barrels are needed. A hammer-forged barrel often delivers very long barrel life, especially when paired with a protective lining. Many such barrels carry a chrome-lined bore for extra durability, though that lining trades a measure of ultimate accuracy for longevity.