white wolf

Two weeks ago, my dad and I were cleaning out my step mother's dad's shed and we found a Vulcan anvil marked with a number 20 on the foot, I guess that is what you would call it. We where told that it was an old gun smith anvil. I was just wondering if anyone could tell anything about them and what the number 20 is about. I thought if anything, the people on here seem well versed on this subject and would give me great info. I would like to say thank you in advanced, for any help.