The number of firearms leapt 22 percent to an all-time high of 2,212 last year, more than triple the number in 2005, the TSA said in its 2014 summary. Eighty-three percent of guns were loaded.
Among the weapons discovered were an assault rifle with three loaded magazines and a loaded folding-stock rifle with two loaded magazines - both at airports in Dallas, Texas.
A loaded .38-caliber revolver was found at New York's La Guardia airport clipped to a 94-year-old man's belt.
Federal law bars bringing a firearm to an airport.
"The most common excuse that we hear from people is that they forgot they had their firearms with them," said TSA spokeswoman Lisa Farbstein.
The number-two excuse for passengers was "'my husband packed my bag' or 'my wife packed my bag,'" she said.
Dallas/Fort Worth International Airport was the top airport for guns discovered, at 120. It was followed by Hartsfield-Jackson Atlanta International Airport, with 109, and Phoenix Sky Harbor International Airport, with 78.
Besides firearms, TSA officers found an Mk 2 fragmentation grenade in Los Angeles, a homemade avalanche control charge in Alaska, as well as fireworks, propane, spear guns, a flare gun, more than 700 stun guns, and smoke grenades.
Bag searches turned up inert explosives and artillery shells, an improvised explosives training kit, a replica Claymore anti-personnel mine, grenade launcher practice rounds and an unloaded cannon barrel.
Officers discovered contraband drugs, razor blades, brass knuckles, throwing stars, scissors and countless knives. An 8.5-inch (21.6-cm) knife hidden in an enchilada was found at the Charles M. Schulz-Sonoma County Airport in California.
TSA screened more than 653 million passengers in 2014, up 14.8 million from a year earlier, the statement said.