What is the value of a Harrington and Richards 16 gage shotgun serial A 395884 and it was my grandfathers so it is around 100 years old.?

In good to very good condition, your grandfather's 16 ga. is worth around $ 70 U.S. to $100. U.S.These H&R's are known to be trustworthy, when properly taken care of, and if it is in good shape, its best value would be as a trusty single bbl shotgun to hunt or protect your home. Be sure to know the proper shell/chamber size. (that should be stamped on top of the bbl just at the break.) these shotguns were made to chamber 2 3/4 shels and two others, i think. Many gun parts dealers on-line can establish your gun's manufacture date with the serial #.

Though it may be old, these guns were made for work, and were never fancy. So what?

One of the most dependable shotguns ever produced, and by a distinguished maker. Keep it up, and pass it along until it is replaced by the Phaser.