The open carrying of firearms is legal in Pennsylvania on paper. There are MANY restrictions on this, including a restriction on having a loaded firearm in your car without having it concealed with a concealed carry permit. Having the firearm in your car without a license to carry firearms can and most likely will result in criminal charges being brought against you and the possible permanent loss of your firearms rights. Yes, there are exceptions for transportation but they are not relevant to this discussion.
Rather than explaining the intricacies of the law and its amorphous forms, please get a concealed carry permit. In most cases a solid argument can be made that if the gun was not visible on three sides you were in violation of the open carry doctrine. Think about coats falling over the holster, sitting down, etc. and you can quickly see the benefits of having a license to carry firearms. It is the opinion of Attorney Benjamin Scott Johns that anyone even considering owning a firearm in Pennsylvania should obtain a license to carry firearms to mitigate some of these issues.
It should also be noted that while I am a staunch advocate of the ability and rights of the citizens to carry firearms within the law, some law enforcement officers and especially the public at large are not aware that this right exists. Many law abiding citizens have been questioned or even had their weapon confiscated because of ignorance of the right to open carry in Pennsylvania. On the other hand, many people who carry do not know the limits that come with open carry and where and when they are allowed to do so. In short, there is almost no reason I can think of that a person who wants to open carry should not also obtain a license to carry firearms in Pennsylvania. It is a simple process and can prevent many legal issues that lacking a license to carry firearms will cause, including criminal prosecution.
PLEASE OBTAIN YOUR LICENSE TO CARRY FIREARMS IMMEDIATELY IF YOU HAVE NOT ALREADY. THERE IS NO GOOD REASON NOT TO OBTAIN THIS LICENSE IF YOU ARE ELIGIBLE. YOU SHOULD ENCOURAGE ALL MEMBERS OF YOUR FAMILY TO OBTAIN ONE WHO ARE ELIGIBLE, EVEN IF THEY DO NOT CURRENTLY OWN A GUN.