Do Executive orders supersede the Constitution

Executive Orders cannot be used to "create law." They can be used in "absence of Law" or to "clarify existing Law" however. The CURRENT LAW specifically allows Person to Person Transfers (what is miscalled the "gun show loophole") therefore "closing it" would be outside the power of an EO.

Everyone focuses on the 2d Amendment, but the real issues with this EO is in relation to the Due Process Clause of the 5th and 14th Amendments. People on the "no-fly" list have not committed a crime, other than come to be watched by the federal government. They have also not had their day in court to determine that they are no longer competent to purchase or own a firearm. Without due process, this is pretty clearly unconstitutional.

Background checks are common sense. (I am a Texan and pro-gun) However, if you try to take any type of gun off the table of ownership by private citizens the next civil war will begin. Why? Read the 2nd Amendment in its entirety. Internalize why it exists. At the heart of the amendment is a group of founding fathers that did not believe in a standing army (of which we were/are a part of). They felt that eventually that standing army could turn against its citizens. In order to allow those citizens to stand up to that standing army, "the right to bear arms shall not be infringed". So why assault weapons? The 2nd amendment is not the protect the right to hunt or sport. It is to protect against a standing army, armed with assault rifles, turning against its citizens.