“SUMMER’S almost here!” the Transportation Security Administration’s chatty blog is currently informing us. That means more people at the checkpoints, of course.


The blog offers many tips for summer travelers, including, “Please get to the airport early to account for the increased passenger load.” Then there is my personal favorite: “Don’t wear clothing with a high metal content.” Right: do not show up at the checkpoint in that suit of armor, all of you medieval festival re-enactors. Just pack it neatly, along with any sunscreen or lotions in excess of 3.4 ounces, in your luggage.


But a useful tip that needs to be more prominently highlighted, in my opinion, is this: Please do not try to take a gun onto an airplane. That is because people in growing numbers are showing up at airport security checkpoints with guns in their carry-on bags.


Five years ago, when passenger traffic was slightly higher, the agency discovered about 500 handguns in carry-on bags at checkpoints. Last year, according to the blog, “Over 1,200 firearms were discovered at T.S.A. checkpoints across the nation. Many guns are found loaded, with rounds in the chamber. Most passengers simply state they forgot they had a gun in their bag.”


So far this year, through last Friday, 513 guns have been found, according to the running count posted each week on the blog, which describes the contraband guns by caliber, by airport where discovered, and by whether or not they were loaded. The vast majority are loaded.


What accounts for the remarkable increase in guns? The T.S.A. will not speculate. The agency says that most passengers found with a gun claim they routinely carry a firearm and simply forgot they had left it in the bag. But clearly the growth also coincides with liberalization of “right to carry” gun laws in many states, and with an overall increase in gun sales in recent years.


When I previously mentioned guns at airports, I said that the last time I routinely carried a gun was when I was required to, in Vietnam. But I live in a part of the country that used to be called the Wild West, where gun-carrying is routine. I’m also a member of the National Rifle Association who knows that a fundamental rule in firearms safety is to always know where your weapon is. So I repeat what I said before, which got some ardent gun advocates very upset with me online: Anyone who forgets that he or she is carrying a gun into an airport checkpoint is a knucklehead.


Common sense tells you that not all the 32 people found with guns (30 of them loaded) at airport checkpoints last week simply forgot they had them. Screeners are amazed at the audacity some gun-toters show. Recently, a handgun was found tucked into a hollowed-out book. In January, a Montana man was arrested after he tried to take not one, but four loaded guns through a checkpoint.


Gun emotionalism being a third rail in national politics, the Transportation Security Administration is astute enough not to get into discussing the motives people might have for deliberately trying to carry a gun onto a plane. “Are more people transporting them that we never caught, and we’re getting better at it? Or are more people just carrying more that we’re catching?” said David Castelveter, an agency spokesman. “That analysis we don’t have. What we know is, we’re catching them.”


Incidentally, it’s unclear how many guns actually do slip undiscovered through security — but the alarming prospect of that happening is tempered by indications that no one with clear terrorist intent has been caught. Yet. Instead, beyond the knuckleheads who just forgot, many of the offenders seem to be people who believe they have a right to carry a gun anywhere.


There are consequences to being caught.


“Every time we catch a weapon, the local law enforcement authority for that airport is notified,” Mr. Castelveter said. “At that point they determine what action they are going to take. Sometimes it may be just detaining and questioning. Other times it may be an arrest, depending on the circumstances.”


In California, gun advocates are up in arms, so to speak, over a bill approved recently by the State Assembly that would require the police to arrest and take into custody anyone caught with a gun in the secure area of an airport. Current laws in California and elsewhere give the police discretion on whether to arrest violators.


The T.S.A. blog describes in detail the weapons and other prohibited items that some of our fellow citizens try to travel with, including hunting knives, grenades and fireworks. And, of course, there is that weekly firearms roundup.


“We do this for a reason,” Mr. Castelveter said. “We want people to realize that if you are trying to get a weapon through you should cease trying, because we’re having great success in stopping you, and we will continue to stop you, regardless of your intent.”