I have in my possession a DiKar Spain 45 Caliber Black Powder Pistol. I would like to learn more about it.?

If anyone is an expert on old guns, and could tell me a little bit more about this gun that would be much appreciated. I have a couple of questions: What is the barrel of this gun typically made of BRASS, STEEL, CHROME??? (I want to know how to clean it properly) What is the difference between a DiKar and a JuKar? When were these guns made and when were they used? Any other info. that anyone has would be insightful.