Several years after his mother was shot and killed and his father wounded in a 2005 rampage by a lone gunman in Thousand Oaks, Christian Heyne went to a gun show in Virginia with a couple of friends.

“I wanted to see if it was true that you could buy a gun without a background check,” said Heyne, who by then was working in the gun control movement.

One of the two friends he was with that day had been shot four times in the 2007 Virginia Tech shooting massacre that left 32 people dead and 17 wounded. The other had lost a sister in that same attack.

Heyne took out his wallet at the gun show and bought a .38 caliber long-barreled revolver, for $250 in cash, from a dealer who placed the gun into a brown bag for him.

“There was no record of the sale,” said Heyne, and no licensing or registration was required. All he had to do was show his ID to prove he was a Virginia resident.

“What makes hate lethal,” said Heyne, now policy vice president at Brady United Against Gun Violence, “is the amount of firearms people have access to without so much as a background check.”

In the three days since I wrote about the carnage in Gilroy, El Paso and Dayton — and about those who tirelessly campaign for stricter gun control — I’ve gotten pushback from a posse of readers. They waved a flag for the right to bear arms of any type and they argued that ownership restrictions wouldn’t make a difference.

I say nonsense.

Nobody should be allowed to buy or possess, under any circumstances, a weapon designed to kill an army of people or a herd of elephants.

Nobody should be allowed to buy a firearm or ammunition of any type, from licensed dealers or from online and gun show sellers, without the same licensing and registration required for vehicles, and without a background check.

Would we still have tragic gun deaths? No doubt. But anyone who discounts the potential benefits of common-sense gun purchase and ownership requirements is not thinking clearly.

In California, Atty. Gen. Xavier Becerra said Tuesday that in the last month, 100 felons and other prohibited people have been prevented from buying ammunition, thanks to background check legislation the gun lobby is trying to torpedo.

For all the readers who wrote me to say the problem is not guns but movies, video games, social media, bad parenting or mental illness, I’d like to respond.

I have no doubt those are factors in some shootings, but the same influences are just as present in countries with far lower rates of gun deaths, and the reason is obvious: they don’t have nearly as many guns as we do, they don’t make it as easy to get them as we do, and they don’t have a militant money-fueled culture of firearm obsession the way we do.

“Mental illness and hatred pull the trigger,” said President Trump, a man with a knack for shanking it off the tee and insisting he hit a hole in one.

Mental illness pulls the trigger? Occasionally, but then why not expand mental health services across the nation and demand red-flag legislation to confiscate the weapons of those in crisis.

Hatred pulls the trigger? No doubt. But please. Trump’s red hat might as well have said Make America Hate Again. You can’t rant about invasions, grin when a disciple suggests the solution to illegal border traffic is to shoot those crossing, and then pretend to walk the high road while graves are being dug.

Shame on him, and on those who keep screaming about their rights to personal arsenals while innocent people get gunned down.

And shame on the NRA and the gun lobby for trying to mislead people with falsehoods.

“Gun crime along with other crimes are highest in cities and states that have the strictest gun laws,” wrote a reader named Mike.

I don’t blame him. I suspect he’s just repeating what he’s heard. But I’d like to refer Mike to the website of the Giffords Law Center to Prevent Gun Violence. There, under the annual scorecard, you’ll find a headline that says: “The evidence is clear — states with stronger gun laws have lower gun death rates, year after year.” You will also find the supporting evidence.

On the Giffords scorecard, California is ranked first in gun law strength and 44th in gun death rate. Alaska, by contrast, is 44th in gun law strength and 1st in gun death rates.

For those who argue that someone can simply buy a weapon in gun-loving Nevada that’s not legal in California and bring it across the border, which appears to be the case in the Gilroy shooting, that’s true. But more restrictions means less availability, and a forced licensing system would help stanch the flow.

I also had readers take me on from the left flank, arguing that nothing short of a repeal of the 2nd Amendment will make a sizable difference in daily bloodshed. But since that’s a politically impossible proposition, I’m for making whatever incremental progress we can in a country where about 100 people die each day on average from firearm suicides, homicides and accidents.

Adam Skaggs, chief counsel and deputy policy director at the Giffords Law Center, said increased funding and development of community violence intervention programs is proving successful around the country. That strategy makes a lot of sense because the mass shootings that get so much attention account for a tiny fraction of gun deaths.

“And while it is certainly true that Congress has not taken any meaningful action to address gun violence in recent years, there has been tremendous progress at the state level in the last five, six years,” said Skaggs. “We’ve made great strides with extreme-risk protection laws and closing domestic violence loopholes, and that critical momentum continues.”

One thing that has impeded progress, however, is that most states have laws that preempt the right of local communities from acting in their own best interest to pass stricter gun controls.

“It’s outrageous that in more than 40 states, local officials on the front lines against violence have had their hands tied to take any action whatsoever, and violence is a localized phenomenon,” said Skaggs, adding that the Giffords Law Center looks for opportunities to challenge preemptive state restrictions either legislatively or through the courts.

In the 2005 shooting in Thousand Oaks, Heyne’s mother, Jan, and father were at the home of a friend when a man involved in a dispute with the friend showed up and began shooting. The man had a violent past, said Heyne, along with a protective order against him.

Heyne said no provision was in place at the time in California for law enforcement to remove a weapon from someone under a protective order, but the law has since been adjusted to make that possible. In most states, Heyne said, that authority is not available to law enforcement.

“I quickly realized it was important to have my voice in this movement and tell my mom’s story,” said Heyne. “Too often legislators are dealing with abstract theories, and it’s important to know the cost of inaction on guns and the lifetime of ill-effects and hurt.”