The ELG means it was made in Belgium, Laminated Steel means basically Damascus, so it will make a nice wall hanger in its condition. With double hammers, side lever and Damascus barrels, I would venture it was made for black powder.
Are there any others beside what you have taken a pic of? It might have been what is called a "guild gun" meaning one small shop made the barrels, one made the action, one the locks, yet another the stock, and finally another assembled the gun (something akin to what GM does with cars)
Here is a chart of Belgian proof marks:
http://damascus-barrels.com/Belgian_All_Proofmarks.html
See which ones, if any, match your gun - look on the water table (which is the top of the action where the barrels sit), top of the barrels, underneath the barrels, etc.