Jani is correct. The trade name was registered while Henri Pieper was still alive. I do not think they continued to use much after 1905. That is when the company was reorganised for the 2nd time and Nicolas left the firm.

http://www.littlegun.be/arme%20belge/artisans%20identifies%20p/a%20pieper%20henri%20gb.htm

It has very little value as a collectible or field gun.

Pete