The president addressed the gun right’s body’s conference in Atlanta, reliving his election triumph but also admitting that his border wall will not be continuous

Donald Trump marked his 99th day as US president by basking in the noisy adulation of his base and making a pledge to the National Rifle Association: “You came through for me and I am going to come through for you.”

The caustic spectacle that powered Trump to victory in last year’s election was on full display before he took the stage in Atlanta, with big-screen ads denouncing his defeated opponent Hillary Clinton, loud boos for former president Barack Obama and speaker after speaker railing against media and Hollywood elites.

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By comparison, the president himself was restrained and even made a concession on his signature policy of building a wall on the Mexican border. “It’s a wall in certain areas – obviously we have these massive physical structures you don’t need and we have certain big rivers – but we need a wall and we’re going to get that wall,” he said. It was the first time he had conceded that the wall would not run continuously along the border.

Trump is more at ease in the company of the faithful – extolling guns, religion and nationhood, suspicious of elites, airing a sense of grievance – than among the suits, concrete and baroque marble of Washington. He will spend his 100th day in office at a campaign-style rally in Harrisburg, Pennsylvania: such raucous events appear to give him a shot in the arm after bureaucratic wrangling with politicians.

“I see all those beautiful red and white hats but we will never forget our favourite slogan of them all: make America great again,” he said on Friday after yet again recounting his election night success.

The NRA was one of his most loyal allies during the 2016 contest. Even as other conservatives balked at Trump’s record, wary of his past support for Democrats and personal scandals, the NRA spent at least $30m, more than any other outside group, to put him in the White House. On Friday he noted that he was the first sitting president to address the NRA at its annual meeting since Ronald Reagan in 1983.

Trump entered to a standing ovation, chants of “USA! USA!” and strains of Hail to the Chief. He struck a more moderate tone than on the campaign trail but could not resist throwing some red meat to an audience of about 10,000 people. He described Democratic senator Elizabeth Warren, a potential opponent in the 2020 election, as “Pocahontas”, a reference to claims she made about being part Native American. The insult was widely seen as racist when Trump used it during the campaign.

The president has been supportive of NRA efforts to weaken restrictions on ownership and promised to scrap Obama’s efforts to strengthen background checks. In a speech thin on legislative achievements but thick on mutual congratulation, he declared: “The eight-year assault on your second amendment freedoms has come to a crashing end. You have a true friend and champion in the White House. No longer will federal agencies be coming after law-abiding gun owners. No longer will the government be trying to undermine your rights and your freedoms as Americans.”

He pledged to defend responsible gun ownership and “protect our wonderful hunters and their access to the very beautiful lands” – he made reference to his adult sons’ love of the outdoors – as well “the sacred right of self-defence” for all citizens.

He ran through a list of his appointments since becoming president on 20 January including Neil Gorsuch, expected to maintain a narrow gun rights majority on the supreme court, and Jeff Sessions as attorney general, already pushing a hardline law-and-order agenda. “Our police and sheriffs also know that when you ban guns, only the criminals will be armed,” he said. “For too long Washington has gone after law-abiding gun owners while making life easier for criminals … We are protecting the freedoms of law-abiding Americans and we are going after the drug gangs and criminal cartels that prey on innocent citizens.”

Trump claimed that, under the homeland security secretary, John Kelly, there had been a 73% decrease in illegal immigration on the southern border; similar assertions in the past have been challenged by fact checkers. Trump claimed he was a victim of his own success and critics were seeking to use this decline to argue against the need for a border wall.

Promising to defend the second amendment, Trump added: “We can’t be complacent. These are dangerous times, these are horrible times for certain obvious reasons, but we are going to make them great times again.”

Before Trump spoke, the crowd was fired up by patriotic country music and a triumphalist film montage on big screens that showed clips of George Clooney, Tom Hanks, Barack Obama, Stephen Colbert, Rosie O’Donnell, Nancy Pelosi and others confidently predicting Trump’s defeat intercut with news coverage of his shock win. The crowd erupted in loud boos for Obama.

Lt Col Oliver North offered an invocation. Chris Cox, executive director of the NRA Institute for Legislative Action, said: “President Trump’s had a hell of a first 100 days.” He added: “We now have a commander-in-chief who isn’t afraid to bomb the ever-loving hell out of Isis.”

On election day, he said, NRA members stormed to the polls in an “act of defiance”. The media even attacked him over the size of his inauguration crowd, Cox said. “I told him the only number that mattered was how many people watched Hillary Clinton’s inauguration: zero.”

Wayne LaPierre, executive vice-president and CEO of the NRA, taunted the academic, political and media elites that he said posed “America’s greatest domestic threats”. He demanded: “When did the media stop being journalists and start becoming PR flaks for the destruction of our country? … Truth is no longer a fundamental principle. It’s now just a political device.”

The NRA has fought back, LaPierre said, by kicking politicians into obscurity, educating citizens about the second amendment and “by giving the media the big fat black eye it so often richly deserves”.

Recycled election commercials attacked Clinton over her handling of the attack on the US consulate in Benghazi, Libya, when she was secretary of state. The audience jeered Clinton’s image but cheered when the ad ended with the NRA symbol and the words “No more lies. Defeat Hillary.” During the election campaign, Trump falsely suggested Clinton wanted to abolish the second amendment.

Guns are allowed in most public places in Georgia, including the Georgia World Congress Center in Atlanta where the NRA meeting is taking place, but attendees were not allowed to bring firearms to the leadership forum where Trump spoke. They were provided with free lockers to store their guns instead.

Facebook Twitter Pinterest Supporters listen to Donald Trump deliver remarks at the NRA Leadership Forum in Atlanta. Photograph: Jonathan Ernst/Reuters

Scott Atchison, 53, wearing a red “make America great again” baseball cap, said: “I voted for Donald Trump because he was the only one talking about the major issues that affect this country: immigration, the corrupt government. Between him and Hillary, there was no choice.”

Atchison, from Decatur, Alabama, who owns 30 guns, is satisfied with Trump’s first 100 days and would vote for him again. “He’s doing well for what he can accomplish on his own but he’s fighting against the globalists, Congress and establishment bureaucracy.”

The high point so far, he said, was attorney general Jeff Sessions’ crackdown on border security and immigration. “If it’s true that he’s not seeking funding for the border wall, that’s the low point because that’s the reason everyone voted for him.”

Michael Temple, 46, a marketing consultant from Toledo, Ohio, said: “I voted for him because I hated Hillary Clinton and I liked his position on some issues. I liked the way the NRA supported him. I think he’s done OK so far. I want to see more legislation get passed. The highlight was his executive order on immigration, even though it got all shot to hell.”

The annual meeting includes a trade show, stores and an airgun range bedecked with stars and stripes and next to a sign with a picture of a squirrel that says: “Protect your nuts.” An on-site shop is selling “NRA country” bags, coasters, flasks, hats, mugs and T-shirts as well as barbecue lighters resembling AR-15 rifles.

Democratic congressman John Lewis, a civil rights leader from Atlanta, had pledged to join gun control activists in Atlanta to protest against what they called “the NRA’s dangerous ‘guns everywhere’ agenda”, which activists blame for contributing to America’s toll of gun suicide and murder that claims an estimated 90 lives each day. About two-thirds of America’s 30,000 gun deaths each year are gun suicides.

There were low-key protests in downtown Atlanta on Friday as people carried signs supporting background checks for gun sales and condemning NRA political donations as blood money. Demonstrators held a “die-in”, lying down on the park’s lawn to symbolise victims of gun violence before marching towards the convention centre.