Much machining I couldn't recognize...vertical mill? The one the young kid was running? The other guy in the beginning was doing screw and pin holes with a jig? All those different drills would be different sizes? Then at 2:45 there's the inspector checking brand new assembled rifles. The ones that are factory correct...the only ones that are factory correct.

It would appear to me that when the barrels are installed, the front sight mortise isn't cut yet. That would be after all is complete...