Bill Clark via Getty Images UNITED STATES - APRIL 14: Rep. Seth Moulton, D-Mass., speaks during the House Democrats' news conference to discuss the post-9/11 GI bill at the Capitol on Thursday, April 14, 2016. (Photo By Bill Clark/CQ Roll Call)

The gunman who killed 49 people and injured 53 at a gay nightclub in Orlando on Sunday was able to inflict such carnage largely because he used a weapon that belongs on a battlefield, not in the hands of ordinary civilians, experts say.

To help settle the ongoing debate about assault rifles’ place in civil society, Seth Moultan, a veteran and congressman, tweeted a photo of himself holding one such weapon while wearing his military fatigues.

I know assault rifles. I carried one in Iraq. They have no place on America's streets. #Orlando

Despite Moultan’s sound argument, gun rights advocates are determined to maintain the laws that protect their access to these weapons of war.

Omar Mateen, 29, used a MCX Sig Sauer, which he purchased legally.

Assault rifles are typically the gun of choice of assailants who wage mass shootings.

ASSOCIATED PRESS Bradley Marvin blows a kiss as he leaves flowers at a makeshift memorial for the five friends he lost along with fellow victims in the mass shooting at Pulse nightclub.

Adam Lanza used an AR-15-style Bushmaster semi-automatic rifle to murder 20 children and six adults in 2012 at the Sandy Hook Elementary School in Newtown, Connecticut. Syed Rizwan Farook and Tashfeen Malik also used assault rifles to carry out the shooting in San Bernardino in December, which left 14 dead.

It makes sense considering the weapon’s capacity.

Initially invented in the 1950s by firearms engineer Eugene Stoner, the ArmaLite Rifle was branded as a lightweight firearm with precision accuracy and high lethality at long range.

They fire off bullets quickly. So quickly that an experienced shooter could fire many as 45 rounds in a minute.

Joe Raedle/Getty Images A Rock River Arms AR-15 rifle is seen on December 18, 2012 in Miami, Florida. The weapon is similar in style to the Bushmaster AR-15 rifle that was used during a massacre at an elementary school in Newtown, Connecticut.

Yet, despite its lethality –- and popularity among mass murderers -- assault rifles remain readily available and nearly immune from policy change.

Two days after the nightclub shooting, it took two HuffPost editors 38 minutes to purchase an AR-15, a gun similar to Mateen's, at a store in Orlando. This, despite the fact that the city was under a state of emergency following the attack.

The salesman told HuffPost that it would typically take five minutes. But because of the surge in sales following the shooting, which is pretty standard, the queue for background checks was longer than usual.

While President Barack Obama has called for bans on such guns, the general public isn’t all that interested in seeing one passed.

According to a December Washington Post/ABC News poll, 45 percent of those surveyed said they want to see assault rifles banned. That’s down from 80 percent in 1994.

And courts continue to side with gun rights advocates on this issue.

In February, for example, a federal appeals court ruled that a ban in Maryland on specific kinds of semi-automatic firearms was unconstitutional.

Outlawing such firearms would “substantially burden this fundamental right” to bear arms, Chief Judge Traxler wrote in his ruling.

Protecting gun rights over actual human lives spurred the Onion, a satirical news outlet, to write a letter of thanks from the perspective of an assault rifle on Tuesday.

“I just want to reiterate how truly grateful I am to the millions of you out there who regularly jump into action at the merest suggestion that any human life might be more valuable than I am, and who stand up proudly and say, 'No, this particular device is far, far more important than someone’s child, than someone’s spouse, than someone’s parent.' And after last weekend, I know I can count on you to do the same again."