I've never had,shot or even really looked at an AR-15 so figured I would seek some info on one I may look at trading for. All I have been told about the gun is that it has a Cavalry Arms complete lower and a Colt complete upper and is a Vietnam style AR (which all means nothing to me) I realize it could have many different parts in it but am just wondering what are some of the things I should beware of or look for in the gun. The trade may be in my favor and I really wouldn't shoot the gun much but just thought it may be good to have around.