I've compared it against pictures on the World Bayonets website and I am confident that it is a Portuguese M1904, probably refurbed. It could possibly fit other incarnations of the Mauser rifle with non standard fittings but that is something that could only be found out by trying. It's amazing how big the Mauser rifle/bayonet empire was before WW2; if the product wasn't directly supplied to countries it was often license made.
