McCarthy, whose career in politics (and passion for gun control) began in the wake of the 1993 murder of her husband by a gunman who opened fire aboard a train, defines large capacity ammunition feeding devices as those with a capacity for more than 10 rounds of ammunition.
"Just as we all celebrate and defend the first amendment but also understand that practical limits must be in place, such as not shouting, 'Fire' in a crowded theater, so too should we be able to respect the second amendment while at the same time supporting commonsense regulations," McCarthy wrote in a 'Dear Colleague' letter on Thursday.
McCarthy told me that she's spoken with an NRA member who explained that sportsman liked using such magazines for target shooting, but she didn't think that reasoning passes muster.
"In all sports, regulations have been put down. Skateboarding, you wear a helmet. Skiing now, they're encouraging children to wear helmets so they're less head injuries. So there are a whole number of regulations out there to protect the public from injuries, and I feel the same way about these large capacity clips," McCarthy said.
"They're still going to be ably to buy clips with 10 bullets and there's one in the chamber, that's 11," she said. "And you know what, and I mean this, we all have to make sacrifices at times for the better good. We've done that time and time again over the years for safety issues, and to me this is a safety issue for the citizens."
While not having access to high capacity clips potentially would have stopped the shooter from taking more lives, he still wouldn't have been prevented from getting the weapon altogether. McCarthy says there needs to be a discussion about what can be done to prevent someone who is mentally ill from getting their hands on a weapon.
"As far as dealing with those that are mentally ill, we are going to be looking at that, but we're going to have to a lot of research on, because there are people obviously who have gone through mental illness who can be worked on with medication and with therapy," she said. "Then you have, it's actually about five percent of the population, that is schizophrenic and delusional, and that's another story."
She told me that "momentum seems to be building" for her bill, which would allow for continued possession of such devices but would ban their transfer or importation, with exceptions made for law enforcement, the protection of nuclear materials, retired law enforcement and authorized testing or experimentation.
McCarthy said she's reached out to House Speaker John Boehner (R-OH) to discuss her legislation -- and the President.
"I talked to Sen. Lautenberg [yesterday] from New Jersey and suggested that we reach out to the president," McCarthy said. "If I didn't think there was any chance on it, I wouldn't be working as hard as I can to try and get it on."
Still, with Republicans in control of the House, it's a steep hill to climb. But the White House said that they're giving the proposals a look.
"As you saw on Wednesday night, the President's focus right now is on the healing process and memorializing the lives that were lost," a White House official told TPM. "There have been a number of proposal put forth in the days since these tragic shootings, and we're going to be taking a close look at all of them. Obviously, reducing gun violence and increasing access to mental health services are policy goals that the President shares."
But while there are plenty of gun control advocates upset with the Obama administration for not making guns a bigger priority, McCarthy said he's had a lot on his plate.
"He did mention it in his speech [Wednesday] night that we need to have a conversation about guns," McCarthy said. "When you really think about what the last couple years have been since he's been in office, we had the financial crisis, we had the health care bill, dealing with Iraq. So I mean he's had a lot of things on his plate, and probably top priority was probably not my issue. But does he believe in these issues? I do believe that."
"Hopefully Sen. Lautenberg and I can convince him that this is the one to take a stand on, because it has nothing to do with the gun, it's an addition to the gun," she added.