To answer the original question, it is not a legal question to ask. Pleading the 5th just indicates you do own one. I suspect that most of the time the person asking that would like to hear that you own none. This would be a great time to spin the question or answer the question with a question!
The 2nd Ammendment of the United States Constitution:
"A well regulated militia being necessary to the security of a free State, the right of the People to keep and bear arms shall not be infringed."
The intent: To allow people the freedom to bear arms, and make it a right and not infringe it. It also helps prevent tyranny (think of what happened in Darfur) which was a main concern of the founders of this then infant country that just fought its way out from under a different tyranny. "People" was defined by DC vs. Heller as an individual person.
It says nothing about for hunting only, or sporting only, of self defense only. It is a very general freedom.
Arms as defined even back in the 1800's were current and up to date military arms which included shoulder fired shotguns and rifles as well as pistols. Cannons are considered "artilery". Explosives are considered "ordinance". Small arms are considered weapons used by an individual person. "The description is usually limited to
revolvers,
pistols,
submachine guns,
carbines,
assault rifles,
battle rifles,
multiple barrel firearms,
sniper rifles,
squad automatic weapons,
light machine guns, and sometimes
hand grenades.
Shotguns,
general purpose machine guns,
medium machine guns, and
grenade launchers may be considered small arms or as support weapons, depending on the particular armed forces."
Machine guns made before 1986 (fully automatic, not semi-automatic), short barreled rifles, shortbarreled shotguns, Destructive devices (over .50 caliber and some shotguns and all grenade launchers), Suppressors (silencers), and AOWs (Any Other Weapon, i.e. pen guns, cane guns, shotgun pistols, pistols with foreward verticle grip etc) are all legal to own in America but they must be registered with the NFA, and you must pay a $200 tax (except for AOWs which is $5 tax), submit fingerprints, passport photos, a big federal form, submit to an FBI background check, and have a Chief Law Enforcement Officer sign off on the purchase and this takes many months and is very expensive. This is so restrictive that in the history of the NFA the only crimes that involved the use of registered machines guns were only two, and one of them was be a deranged cop.
The BATFE regulates all firearms, tobacco, alcohol, and explosives in the US. Explosives in the form or grenades, grenades that get launched, rocket warheads (like used in bazookas) and all other forms are so heavily restricted that only the military or MAYBE some police depts can buy them. These things can not be purchased at gun shows or gun stores, and if they end up in Mexico it was because they were stolen from the military.
I think a large percentage of gun related crimes (100% to be exact) would be reduced if the person using the gun simply did not commit the crime. The only argument that makes sense is that guns may (not always) increase the efficiency of a criminal killing. That being said, if all guns were banned, I would highly expect to see an increase in killings using kitchen knives etc.
As to gun laws, if the current gun laws were enforced 100% then we would not be having many problems. The solution: do a better job enforcing current laws. What good would more laws do as long as the criminals were not concerned about breaking the laws in the first place which first made them criminals?