Amid collections of pistols, tactical assault rifles, vintage shotguns and rifles at this year’s Tombstone Gun Show, John Berend sold T-shirts supporting the right to bear arms.

“If you change the Second Amendment, what’s to stop them from changing the First?” a printed statement on one of Berend’s shirts read. On another: “I carry a gun because a cop is too heavy.”

While the slogans on Berend’s shirts highlight many of the key issues in the debate over gun control like last year’s Supreme Court decision that amended the right of individuals to bear arms for personal use, they did not address the growing criticism that gun shows put firearms in the hands of criminals.

Recently, New York Mayor Michael Bloomberg put gun shows in the national spotlight when he launched an investigation into a supposed “gun show loophole” to find out if it was possible for those with criminal records to purchase firearms at gun shows without undergoing a background check.

In a 36-page report released earlier this month, Bloomberg’s office documented alleged illegal gun sales by private and licensed dealers at seven gun shows in three states.

Hidden cameras show unlicensed dealers selling guns to undercover investigators after they told the seller they would probably not pass a background check. The tapes also show authorized dealers selling guns to investigators who said they were buying the weapon for someone else. Only 25 percent of the purchases were denied, according to the mayor’s office.

Charles Heller of the Arizona Citizens Defense League said the idea behind a gun show loophole is false and does not take into account the letter of the law.

“A transaction that takes place between two people outside of a gun show is no different than what takes place inside of a gun show,” Heller said. “If it’s legal out there, it’s legal in here. There is no loophole whatsoever.”

By law, gun sales are permissible between two private persons as long as the seller has a “reasonable belief” the purchaser is eligible to own a firearm. Eligibility is determined by roughly ten stipulations that include: meeting minimum age requirements; a record clear of any felony convictions or domestic violence charges; a person must also be legal resident and not dishonorably discharged from the military.

“If you ask a person (if they are eligible) and he even hesitates when they say it, nobody in their right mind is going to sell them a gun,” Heller said.

“Do they have to ask? Technically, no,” Heller added. “Must they ask in order to have a reasonable belief? Unless they know the person, yes.”

Peter Tapia, a salesman for Pima Guns, said he is required to perform a background check before he sells someone a gun at a show because his employer holds a Federal Firearms License.

The background check process takes about 10 minutes and can be done over the phone while the customer waits.

But Tapia said unlicensed dealers, who by law do not need to perform a background check, are not likely to sell the high-powered semi-automatic rifles and pistols Pima Guns and other licensed dealers offer.

Unlicensed sellers, he said, are typically collectors of vintage guns who use gun shows as a way to enhance their collections or to sell to other discriminating enthusiasts. Tapia added that such vintage guns aren’t the type that are favored by criminals or are used by gangs and in street crime.