I was looking at a Ti receiver the other day and started wondering how you finish it.

Thaks

Paint, but watch out for flourocarbons.  They do not mix well with Ti.  While CFCs are no longer used as aerosol propellants, related chemcals found in some markers can also cause Ti corrosion.
Chrome is another problem with Ti.  no chrome plated tools should be used on Ti parts.
Some of the problems only occur at higher temps, but chrome is a no-no at any temp.

Cadmium is the problem metal for stress corrosion cracking of Ti.
Looked it up in my corrosion control manuals.
Cadmium can cause stress cracking if Ti without an underlying defect and without warning.  The Cd enters the grain boundaries of the Ti and causes weakening.

try www.metalfinishing.com