Critics are piling on the National Rifle Association after the group compared assault-style weapons to the muskets used during the American Revolution.
"The AR-15 is the modern day musket. An everyday gun for everyday citizens," the NRA said on Twitter.
The reaction to the Saturday tweet was swift.
David Hogg, who was a student at Marjory Stoneman Douglas High School in Parkland, Florida, when a 19-year-old gunman opened fire and killed 17 people, said on Twitter: "6 minutes 20 seconds Is all it took for the shooter at my high school to fire over 100 rounds from his AR-15 to shoot 34 people."
"In that same amount of time even the most trained person would have only been able to fire 18 rounds with a musket," Hogg wrote.
This isn't the first time the NRA compared the AR-15 to a musket. Saturday's tweet used the same language as a 2016 online article from the NRA's Institute for Legislative Action.
"In truth, the AR-15 is the contemporary equivalent of the musket - an everyday gun for everyday citizens. Fundamentally, the AR-15 is democratic. It is the yeoman's gun; the people's gun; the Brown Bess of our era," National Review editor Charles Cooke wrote for the NRA.
Fred Guttenberg, whose daughter was killed in the Parkland shooting, replied to the NRA's recent tweet: "The AR-15 is the modern weapon of choice for mass murders. It was used to kill my daughter and 16 others in school in 6 minutes. An everyday gun for those who want to kill as many as possible."
Zach Elmore, who said his sister was wounded in the Mandalay Bay shooting in Las Vegas, tweeted, "I'd have liked my sister's chances a lot more if a guy shooting from the 32nd floor of the Mandalay Bay was using muskets instead of AR-15s. Instead, 58 were killed and my sister still has bullet fragments in her back."
Assault weapons were not allowed to be sold in the United States until the ban expired under President George W. Bush in 2004.
Assault-style weapons have become a symbol for some in the pro-gun movement.
Absent a federal assault weapon ban, some areas have decided to ban the guns locally. The Supreme Court this year refused to hear a case over a Cook County, Illinois, law that banned some semi-automatic rifles, handguns and shotguns, according to Patch.com. A federal appeals court earlier upheld the law, so that decision stands.