Welcome to the Gunboards Mauser Forum. You have a very nice Mauser carbine. It is one of about 180,000 Mauser Model 1889's made by Hopkins and Allen in Norwich, Connecticut between 1916 and 1918 for the Belgiam Army. Your rifle, a Model 1916, was one of only 10,000 carbines made at the end of the production contract. (The rest were long rifles with 29 inch barrels.) At the time your carbine was made, the original firm, H&A, had gone bankrupt, and their contracts, tooling and properties in Norwich had been purchased by Marlin Rockwell. All H&A Model 1916 carbines had a letter "R" in the serial number. Unfortunately, the bolt on your carbine is mismatched, reducing the value somewhat. However, it is still very collectible. All 10,000 H&A Belgian carbines arrived in Europe just as WW I was ending, so none of them saw combat service during that war. However, they certainly could have seen colonial service and WW II service in Europe. Most Model 1916 Belgian Mausers were made by firms in Belgian, like Fabrique Nationale. There are a few existing photos showing Model 1916 carbines issued to WW II German troops not serving in front line units.
Your bolt's serial number identifies it as a correct Belgian Mauser carbine bolt, although it is not made by H&A. The E/GB mark is the carbine's proof test mark. The three letter abbfreviation stands for a French phrase which translates as "Belgian Government Proof".