What qualifies a gun as a pistol instead of an sbr? I realize it’s usually weather or not it has a stock or brace but Is there an overall length that it cannot exceed? Are there any attachments that make a pistol an sbr? Like a forward hand grip or law folding stock adapter etc? I have a springfield saint pistol that I would like to do some things to but don’t want to break any laws. I live in Pennsylvania.