The three cannon balls and 700Kp/cm h*2 is a Spanish Black Powder Proof mark.
Ardesa is a Spanish company that has made muzzleloaders for CVA and Traditions for years.
They not only supply guns to these American distributors but they sell many of their guns in Europe and the U.K.
Without photos of your gun it is difficult to nail down just exactly what you have but generally speaking the Ardesa guns are low cost and very functional.
There are better guns made but dollar to dollar the Spanish guns are worth the money.
Again, generally speaking these guns will have a 1:48 twist that is suitable for shooting patched roundballs or lead slugs.
If you decide to shoot your gun it would be happy with a .490 diameter pure lead roundball patched with .015 thick pure cotton patches.
The patches can be lubricated with spit, Crisco, Olive oil, Castor oil, or one of the lubricants made for muzzleloading guns by several different makers.
Because your gun is a Caplock, or percussion gun it will work with Pyrodex, 777 or one of the other synthetic black powders. It will work best with real black powder in the FFg or FFFg granulation size.
A word of warning here: NEVER try to use ANY SMOKELESS POWDER of any kind in your gun.
It will explode from even the smallest load of modern smokeless powder.
Because many of the modern smokeless powders are colored black some unfortunate people think that they are all right to use in their muzzleloaders.
They are NOT.
A load which will work well with the .490 diameter roundball would be 60-75 grains of powder.
This powder should be measured with a powder measure which can be purchased at gun stores which deal in muzzleloading arms.
Your gun will use a standard #11 percussion cap to ignite the powder charge.
The recoil from firing your gun with the above powder/ball load will be slightly less than you could expect from a .30-30.
Black powder guns recoil is also different when compared with modern smokeless cartridge guns.
Rather than a sharp WHACK on the shoulder black powder guns give a quick hard push which makes shooting them much more enjoyable than modern guns.
A tongue in cheek warning though.
If you take your new gun out and shoot it you will find that it is so much fun that you will be hooked for life.
The first shot is usually the greatest.
A look of doubt on the face. The careful aiming. The thoughts that this old fashioned thing probably won't work. Then the BOOM followed by a large cloud of white smoke and an ear to ear grin!
If you decide to shoot it, feel free to ask any question you may have. We will be more than glad to answer anything you want to know.