By MALCOLM GAY

NASHVILLE — Happy-hour beers were going for $5 at Past Perfect, a cavernous bar just off this city’s strip of honky-tonk restaurants and tourist shops when Adam Ringenberg walked in with a loaded 9-millimeter pistol concealed in the front pocket of his gray slacks.

Mr. Ringenberg, a technology consultant, is one of the state’s nearly 300,000 handgun-permit holders who have recently seen their rights greatly expanded by a controversial new law — one of the nation’s first — that allows them to carry loaded firearms into bars and restaurants that serve alcohol.

“If someone’s sticking a gun in my face, I’m not relying on their charity to keep me alive,” said Mr. Ringenberg, 30, who said he carries the gun for personal protection when he is not at work.

Gun rights advocates like Mr. Ringenberg may applaud the new law, but many customers, waiters and restaurateurs in this city are dismayed by the decision. “That’s not cool in my book,” said Art Andersen, 44, as he nursed a Coors Light at Sam’s Sports Bar and Grill near Vanderbilt University. “It opens the door to trouble. It’s giving you the right to be Wyatt Earp.”

Tennessee is one of four states that recently enacted laws explicitly allowing loaded guns in bars. Eighteen other states allow weapons in restaurants that serve alcohol. The new measures come amid two landmark Supreme Court rulings that citizens have an individual right — not just in connection with a well-regulated militia — to keep a loaded handgun for home defense.

Experts say these laws represent the latest wave in the country’s ongoing gun debate, as the gun lobby seeks, state by state, to expand the realm of guns to include nearly every aspect of civic life.

The rulings, which overturned handgun bans in Washington, D.C., and Chicago, have strengthened the stance of gun rights advocates nationwide. More than 250 lawsuits now challenge various gun laws, and Gov. Rick Perry of Texas, a Republican, called for guns to be allowed on campuses after a shooting last week at the University of Texas at Austin.

The new laws in Tennessee, Arizona, Georgia and Virginia have also brought to light the status of 20 other states — New York, New Jersey and Massachusetts among them — which do not address the question, appearing by default to allow those with permits to bring guns into establishments that serve alcohol, according to the Legal Community Against Violence, a nonprofit group that advocates gun control and tracks state gun laws.

“A lot of states for a long time have not felt the need to say you could or couldn’t do it,” said Paul Helmke, president of the Brady Campaign to Prevent Gun Violence. “There weren’t as many conceal carry permits out there, so it wasn’t really an issue.” Now, he said, “the attitude from the gun lobby is that they should be able to take their guns wherever they want. In the last year, they’re starting to move toward needing no permit at all.”

Tennessee State Representative Curry Todd, a Republican who first introduced the guns-in-bars bill here, said that carrying a gun inside a tavern was never the law’s primary intention. Rather, he said, the law lets people defend themselves while walking to and from restaurants.

“Folks were being robbed, assaulted — it was becoming an issue of personal safety,” said Mr. Todd, who added that the National Rifle Association had aided his legislative efforts. “The police aren’t going to be able to protect you. They’re going to be checking out the crime scene after you and your family’s been shot or injured or assaulted or raped.”

Under Tennessee’s new law, gun permit holders are not supposed to drink alcohol while carrying their weapons. Mr. Ringenberg washed down his steak sandwich with a Coke.

But critics of the law say the provision is no guarantee of safety, pointing to a recent shooting in Virginia where a customer who had a permit to carry a concealed weapon shot himself in the leg while drinking beer at a restaurant.

“Guns and alcohol don’t mix. That’s the bottom line,” said Michael Drescher, a spokesman for Governor Phil Bredesen of Tennessee, a Democrat, who vetoed the bill but was overridden by the legislature.

The law allows restaurant and bar owners to prohibit people from carrying weapons inside their establishments by posting signs out front. But many restaurateurs are reluctant to discourage the patronage of gun owners, often saying privately that they do not allow guns, but holding off on posting a sign.

“I’ve talked to a lot of restaurants, and probably 50 to 60 percent of them have no clue what’s going on,” said Ray Friedman, 51, who has created a Web site listing the firearms policies of area restaurants.

Previously, states like Tennessee did not allow its citizens to carry concealed weapons unless they had a special permit from local law enforcement. That began to shift in the mid-1990s, as the gun lobby pushed states to adopt policies that made permits for concealed weapons more accessible.

The new law passed with broad legislative support, despite opposition from the Nashville Chamber of Commerce and the Tennessee Hospitality Association.

So far, there has been only one challenge to the new law. Filed by an anonymous waiter, the complaint contended that allowing guns into a tavern creates an unsafe work environment for servers. His complaint was denied by the state’s Division of Occupational Safety and Health.

“A loaded concealed weapon in a bar is a recognized hazard,” said David Randolph Smith, a lawyer who represents the waiter and is preparing to appeal the decision. “I have a right to go into a restaurant or bar and not have people armed. And of course, the waiter has a right to a safe workplace.”

Down at Bobby’s Idle Hour, however, Mike Gideon said he did not believe that guns in bars were unsafe. As he sipped a beer in the fading afternoon light, Mr. Gideon, who characterized his 19-gun collection as “serious,” said that having a few permit holders around made any public space safer and that he boycotts any business that does not allow him to carry a weapon.

“People who have gun permits have the cleanest records around,” said Mr. Gideon, 54, who said he applied for his permit to carry a weapon in the days after President Obama was elected. “The guy that’s going to do the bad thing? He’s not worried about the law at all. The ‘No Guns’ sign just says to him, ‘Hey, buddy, smooth sailing.’ ”