This vintage mouthpiece is marked 100-2-M. I measure the tip open to be 0.100″. I measure the facing length to be 25mm. That 25mm seems none too long for a Berg bari marked “M”.
It shows signs of handcrafting. The facing numbers look they were each stamped on individually. Have you ever wondered why the facing length designation is offset? Perhaps it was done at a different time from the rest of the fabrication?
The outside of the mouthpiece show handfinishing, like where the shank transitions to the body.
And the bullet-shaped cutout looks like it was done “by hand”…or at least by a handheld on hand directed machine.