Well, the 792 is 8mm Mauser and the crest is a Spanish La Civile Gaurdia ... BUT that rifle is around 100 years old and many people rebarreled, sporterized, etc them into other configurations but the barrel technically should be marked but do not count on it either. Before you do anything you need to determine what it is chambered for now by slugging the barrel. Also you should check the head spacing once you verify the chambering. Honestly I would not trust my eyes, face, hands, etc to fire it without having a smith check it out.