Carry-on bags at checkpoints have been pulled from conveyor belts in U.S. airports nearly 1,750 times this year because they contained a gun, often loaded, according to the Transportation Security Agency.

John Pistole, the TSA administrator, said that amounted to an average of about five weapons a day uncovered by screeners. Many of those guns are loaded.

"There's a procedure for anybody who wants to transport a gun on an airplane to put it in a checked bag, not through the carry-on, obviously. You can't take it in the cabin of the aircraft. … You have to declare it to the airline. You have to have it unloaded. You have to have it in a locked solid container in your checked bag," Pistole said.

Related: TSA confiscates 4 guns a day

The number of guns confiscated by the TSA has skyrocketed from 660 in 2005 to double that in 2011 - and nearly triple that in 2013.

The TSA said the increase was possibly tied to the fact that the number of weapons Americans carry continues to rise, up 16 million last year alone.

Airports in Atlanta and Dallas saw the most confiscated guns.

None of the weapons confiscated in 2013 was intended to be used on a plane. Pistole said the travelers found with weapons in their carry-on baggage were not terrorists or people trying to do harm.

"It's just a matter of people not thinking about what they're carrying. … These are people who have simply forgotten and go through [security checks] and then realize their mistake," Pistole said.

In fact, the last time a gun was fired during a domestic flight was in 1987 when a PSA jet was brought down by a gunman in the cockpit.

Still, guns on board planes remain illegal and it's not just guns. Everything from knives to swords to mace and grenades were also captured this year.

Slideshow: TSA's "unusual" confiscated items.

Brass knuckles, even if installed as an accessory on a purse, are illegal to bring on a plane and if the weapon is artfully concealed, for instance in a cane or inside of a book, the charges can be even more serious.

Pistole said fliers found with weapons in their carry-on bags faced possible fines and arrest and a forfeiture of their guns.

"Our request is that before you pack to stop and think what you're packing and then to travel accordingly," he said.