Very early on in the Titanium gun business an unusual thing about Titanium turned up...... Rifling in Titanium barrels tended to "fade".
Titanium is a metal that has a strong tendency to try to return to it's original shape, and the rifling tended to sort of "melt" and fade back toward a smooth shape.
The rifling was still there, but so rounded as to not grip the bullets very well, and bullets tended to "strip" instead of being gripped by the rifling.
For that reason, Titanium barrels are actually a Titanium outer shroud, with a pressed-in stainless steel rifled liner.