
CNN
—
California has some of the strictest gun laws in the country, according to advocacy groups. And yet the state has been rocked by three mass shootings in 44 hours.
At least two of the suspected gunmen carried out the attacks with semi-automatic weapons, and at least one of the weapons was currently illegal in the state.
We spoke with CNN’s Guns in America contributors Jennifer Mascia and Stephen Gutowski to learn more about the firearms used in each attack.
The questions and answers below have been lightly edited for clarity and brevity.
The weapon used in the attack was either a MAC-10 semi-automatic assault weapon or a Cobray M11, according to authorities (they said both). What does this mean and are these types of guns legal in California?
JM: First, a caveat: An original MAC-10, the Military Armament Corporation Model 10, is normally a fully automatic machine gun. This means multiple bullets are fired per trigger pull.
Machine guns are heavily regulated by the National Firearms Act. The weapon he used was not a machine gun. Variants of the MAC-10 include the Cobray M11/9, which was originally reported to have been fought away from the gunner.

MAC-10 variants are illegal under California’s assault weapons ban for two reasons: they have a threaded barrel and are designed to carry 30-round magazines. Anything over 10 rounds is illegal under California law.
GS: It appears that the gun that was taken from him had a suppressor/silencer attached, which means it likely had a threaded barrel that would make it illegal to purchase today.
It’s also not legal to buy today because California has banned the sale of guns without certain features, such as a magazine safety, loaded chamber indicator, or “microstamping” technology (which no gun company actually produces).
However, the suspect in this case is 72 years old, and the ATF trail indicates that he purchased the gun himself. We need more information about when the purchase was made. But since the company that made it went out of business in the 1990s, it’s possible you bought it legally before California’s “assault weapons” ban went into effect.
How the Monterey Park shooting and the hunt for the gunman unfolded
Has any modification been made to the weapon? If so, did it make it more dangerous and/or illegal?
GS: CNN’s report suggests police believe he was illegally manufacturing suppressors, also known as silencers, at home. The video of him being disarmed by Brandon Tsay shows what appears to be a suppressor attached to the end of the barrel. California…has a total ban on even the possession of suppressors. So it wasn’t legal for him to have it.
Silencers reduce the sound of gunshots. However, they don’t actually silence a shot. Depending on the caliber and effectiveness of the suppressor, they generally reduce the sound to the same decibel level as a jackhammer. Suppressors work exactly the same way car mufflers do and were invented by the same person (Hiram Percy Maxim).
How was he able to fire so many rounds?
GS: Police say the shooter used a 30-round magazine, which California also bans from new sales. Given the suspect’s age, he may also have purchased the magazine before California instituted its ban several decades ago.
California passed a confiscation law banning the possession of magazines that hold more than 10 rounds in 2016. However, a federal judge blocked its enforcement out of concern that it violated the Constitution and this case (Duncan v. Beccera ) is still working on the process. courts
Additionally, survivors report that he also reloaded during the attack. So the size of the magazine didn’t stop him from having to reload the gun at least once.
Also, the gun he used can fire rounds at basically the same rate as any other semi-automatic firearm (one shot per trigger).
The gun had a long barrel on the end – what is that and what does it do?
JM: I think this is a silencer that muffles the sound of a gunshot. But this has not been confirmed by law enforcement. Silencers are regulated by the same federal law that regulates machine guns. He would have had to register the device with the federal government to be the legal owner.
Authorities have said the gun was a semi-automatic weapon, legally registered to the shooter. How is this gun different from the semi-automatic used in the Monterey Park shooting and why is it legal and the other is not?
JM: The Monterey Park gun is not legal in California because it has functions prohibited under the state’s assault weapons ban: a threaded barrel and is designed to carry 30-round magazines.
The gun used in the Half Moon Bay shooting was a registered semi-automatic handgun that had none of the features listed in California’s assault weapons ban. Most handguns in circulation are semi-automatic, meaning that another bullet is automatically moved into the chamber after firing. It does not have to be cocked manually, like a revolver.
What does the number of casualties tell you about the type of weapon used?
JM: AR-15s are particularly deadly, so they leave fewer survivors, but most mass shootings are actually perpetrated with handguns. The Half Moon Bay shooting was so deadly probably because he targeted his victims and shot them at close range.
With the Monterey Park shooting, I knew right away that the gunman wasn’t using an AR-15 because there were so many survivors. A MAC-10 variant and other “assault pistols” are closer in lethality and functionality to a pistol than an AR-15. They are old, heavy and not very accurate weapons, so the death toll was more like a handgun attack than an assault rifle.
Authorities said the suspect in the Half Moon Bay shooting legally had his gun and was targeting specific people.
GS: Unfortunately, when an armed person attacks a group of unsuspecting and unarmed people, it doesn’t take any kind of weaponry or advanced tactics to inflict a horrific toll on a community. Mass killings have been carried out with all kinds of weapons, from rifles and semi-automatic pistols to shotguns, to bolt-action rifles, to knives or blunt instruments.
That’s the number of mass shootings there have already been this year
So far, police have found no weapons, only shell casings. Can they trace the type of weapon with these casings and/or the victim’s wounds?
JM: The casings can be run through NIBIN, the ATF’s ballistics database, to connect them to casings found at other shooting scenes. But NIBIN does not produce the serial number or chain of custody of a weapon. However, it can connect shooters across jurisdictions and prevent repeat shooters from striking again.
GS: Police can identify what caliber of gun was used in the attack from the bags recovered at the scene or from the victims’ injuries. However, it is much more difficult to determine the specific firearm used in an attack from spent casings or wounds alone.