This is one procedure that you do not expect to see at a normal gun manufacturing facility. But remember, the Winchester Repeating Arms / FN Manufacturing facility is no ordinary factory. This is place that is used to doing things to a level of quality and precision not found on production American sporting rifles.
FN Manufacturing (FNM) employs a robot polishing machine to finish the barrel making process. It takes a stack of barrels and systematically runs them through a sequence of polishing processes from fine to super fine, to achieve a mirror polish.
The robotic polisher goes through the three-stage process.
Bluing -- the final step.
The secret to good bluing is two fold. First, polish to the highest level possible and second prevent too much oxidation from occurring between polish and bluing. On the Model 70 you get both. The barrel profiled barrels enter the polisher in a state that is acceptable to most manufacturers and leave with perfection.
After polishing, the barrels are screwed back into the receiver for the last time. Lock-tite is used on the threads, not just to keep the barrels on, but mostly to prevent bluing salts from getting into the threads. This is a quality touch ignored by lesser gunmakers.
A gunwriter inspects a barrel and receiver during a tour of the factory.
With the barrel and receiver matted again, they go to be blued. In the plant this is called “black oxide.” But bluing and black oxide are the same thing.
Below is video footage of the Model 70 barrel polishing robot. This video was taken at a gunwriters event held at the Winchester/FNM factory where the barrels are made. At the factory barrels are hammer forged to create the rifling, turned on CNC machines to the desired profile, chambered, crowned, polished on the robotic polisher (shown below) and finally attached to a Model 70 action.