Stainless Steel Barrel
Also: 416R
A barrel made from corrosion-resistant stainless alloy, typically 416R, which machines cleanly and dominates precision-rifle production.
A stainless steel barrel is made from a corrosion-resistant alloy, most often the 416R grade developed specifically for barrels, with its sulfur content tuned so the steel cuts cleanly. That machinability lets makers cut, ream, and lap a smoother, more uniform bore, which is a large part of why stainless dominates the precision and match world. The chromium in the alloy resists rust well enough that many such barrels are left in the bare metal.
Compared with chrome-moly steel, stainless tends to finish to a finer surface and is the default for match-grade work, though it is not truly stain-proof and still benefits from basic care. The two steels are similar in strength, so the choice usually comes down to finish, machinability, and the level of accuracy a shooter is chasing.