Are you a permanant resident and hold a green card? If so, you can purchase a gun in most states. Not all states have the same laws so check the laws of the state you are in.
If you don't hold a green card, you may need to get a hunting licence before you purchase a gun. Check the laws of the state you are in.
If you are an illeagal alien; forget it.
Gun laws vary widely throughout the US. What is leagal in one state could land you with a prison sentance in an other. Some states put a limit on how many rounds a magazine can hold and others don't care. Certain guns require special tax stamps to own. These are machine guns, short barrel rifles, sawed off shot guns and silenced weapons. Some states allow these and other do not.
You sugested that you own a bussiness in the US. If so, you are probably already a permanent resident. Go to your local gun shop and ask what you can get. The owner of the gun shop will hold a Federal Firearms Licence. He will be able to inform you of both Federal and State laws that apply to you and what paper work you will need to buy a gun.
