Is that a "twisted" barrel? Damascus?
Just my 2 cents. How old is old? Looking at the rust pattern that is showing up it may be a Damascus barrel. Either way get it checked out by a real gunsmith first. Your life is worth more than the thrill.
How would I go about telling? The only markings I see is the model "Revelations Model 350 Series K" and a "P2XXXXX" serial and "Proof Tested 12 Gauge 3 inch Chamber" on the gun.