I'm sorry Tom, but your gun is a lower quality Belgian made Tradename gun and in no way connected to Parker Brothers of Meriden, Conn. Tens of thousands of similar guns were imported between the 1890s and beginning of World War I, and were engraved with the name of a well recognized maker in the hope of confusing the purchaser. Other examples include the Sam Holt, W. Richards, and T. Barker and images may be seen here
http://www.picturetrail.com/sfx/album/view/20091267
As a family legacy it is of course priceless; as a sporting arms it has very little value and you should not attempt to shoot the gun with ANY load.