Ed is right. The Spanish city of Eibar is the center of the Basque gunmaking trade, and is home to such world-renowned firms as Garbi, Arrieta, AyA, Grulla, Ugartechea and Arrizabalaga. They all produce fine guns that anyone would be proud to own. However, throughout history there have been many conglomerations with various levels of quality operating there. Some produce low-quality guns under generic names to save their reputations; others make great guns bearing different lables. Hard to say what you have. Perhaps you could share the proof marks with us? And a few photos?

As an example of what you can expect from the region, the gun below was hand-made in Eibar by Grulla.