The gun show draws a bigger crowd than an impromptu memorial to five police officers murdered in downtown Dallas - and as a convulsive new civil-rights debate leaves the country's most effective new activist group, Black Lives Matter, reeling; even the powerful National Rifle Association is on the ropes.
As thousands streamed through the cavernous Lone Star Gun Show at Fort Worth, a 30-minute drive east from Dallas, and flowers and other mementos were piled on two police cruisers outside Dallas police headquarters, there were pleas for calm after a wave of tense and noisy protests across the country in which hundreds of demonstrators were arrested.
In Dallas, Police Chief David Brown said written evidence of planning for attacks "large enough to have devastating effects throughout our city and our north Texas area" had turned up in a search of the home of the gunman Micah Johnson, whose death in a police bombing in the early hours of Friday ended a horrific downtown drama.
Brown said that Johnson's planning was well advanced before the outrage sparked by police killing two African Americans last week. "He thought what he was doing was righteous [as he planned to] target law enforcement, and make us pay for what he saw as law enforcement's efforts to punish people of colour."
Investigators were mystified by one of Johnson's last acts - wounded before the detonation of the bomb that killed him, Brown said Johnson had used his own blood to daub the letters "RB" on the wall of a parking garage in which he was holed up.
The meaning of the letters were not known.
On Sunday, President Barack Obama, who has spoken sympathetically on BLM's cause, warned that attacks on police would hurt the movement because there would always be people who would make "stupid" or "over-generalised" remarks.
"Whenever those of us who are concerned about failures of the criminal justice system attack police, you are doing a disservice to the cause," he said in Barcelona, Spain.
DeRay Mckesson, a high-profile BLM leader, was one of 125 people arrested in Baton Rouge, where one of the police killings took place.
Police said Mckesson had been arrested for blocking a street, even as video he was live-streaming as he was detained indicated that he was off the roadway.
Before the Dallas bloodletting, BLM seemed to be on a roll - its blunt messaging and disruptive protests were provocative, but their message was getting traction, as exemplified after one of the police deaths in Minnesota last week, when white state governor Mark Dayton asked in public: "Would this have happened if those passengers - the driver and the passengers - were white? I don't think it would've."
But after Dallas, all seemed to go pear-shaped. BLM was under attack from conservative broadcasters and politicians.
In Texas, Lieutenant Governor Dan Patrick claimed BLM was directly responsible for the police deaths because it had created the conditions for the attack. And Republican state congressman Bill Zedler tweeted: "Clearly the rhetoric of Black Lives Matter encouraged the sniper that shot Dallas police officers."
In Chicago, Pastor Jedidiah Brown who has become an articulate BLM activist, told The New York Times: "What I saw in Dallas was devastating to our work." He said he quickly sensed that any emerging national consensus would "tear down the middle".
The needle that BLM must now thread is to create a narrative by which it can distance itself from the Dallas gunman who set out to kill white police officers, more in the name of the hate groups he tracked on Facebook than that of BLM; and at the same time, promote the lopsided experience of African Americans whose chances of being arrested, jailed and shot by a police officer are significantly higher than for white Americans.
A weekend statement by the BLM Network made a raw attempt: "There are some who would use these events to stifle a movement for change and quicken the demise of a vibrant discourse on the human rights of Black Americans. We should reject all of this."
A difficulty for BLM is that, in recounting some of the exchanges between the killer Johnson and police negotiators, Dallas police chief Brown said that Johnson had no direct links to particular movements, but he also said Johnson "was upset about Black Lives Matter", without clarifying the fogginess of that statement.
Before his arrest in Baton Rouge, Mckesson told a reporter that on Thursday night he had been monitoring the increasingly sympathetic debate on social media, but with dismay he watched the tone change rapidly as news came out of Dallas.
"It suddenly became about blame. People wanted to link it to the protesters no matter what."
Some BLM activists went on the offensive, like Ja'Mal Green who argued that the Dallas killings needed to be seen as a wake-up call.
"It's not a setback at all," he told The New York Times. "That's showing the people of this country that black people are getting to a boiling point. We are tired of watching police kill our brothers and sisters. We are tired of being tired."
Meanwhile, the NRA, which was quick to be heard on the Dallas police killings, was under challenge from an array of liberal and conservative rights activists for its silence on what should be one of its campaign staples - the rights of a law-abiding gun owner who just happened to be black.
That would be Philando Castile, the man killed by a police officer in St Paul, Minnesota, last week who had a licence for the gun he had told police he was carrying as he was shot dead.
The issue here is that the NRA is strongly aligned with law enforcement and is seen as a predominantly white and conservative organisation.
The host of an NRA News talk show, Cam Edwards, argued after the Castile killing but before the Dallas killings, that it was a huge issue if black gun owners were reluctant to go armed because they feared the police would target them.
"Self-defence is a human right," he said. "Our right to keep and bear arms is not based on the colour of our skin."
