The shootings in Aurora, Colorado, have reignited a debate about gun control and whether the now-expired federal Assault Weapons ban that would have covered one of the rifles used in the theater could have prevented the tragedy.

On CNN’s State of the Union this Sunday, Sen. John McCain (R-AZ) explained that while “we need to look at everything,” gun control measures may not prevent mass gun violence:

MCCAIN: We had a ban on assault weapons, it didn’t change the situation at all in my view…. Look, I think that the strongest second amendment rights people would be glad to have a conversation. But to somehow leap to the conclusion that this was somehow caused by the fact that we don’t have more gun control legislation I don’t think has been proved.

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But McCain was once a gun control advocate. He served as a spokesman in the early 2000s for Americans for Gun Safety, a campaign that encouraged states to enact stricter regulations. In 2004, McCain broke with his party to vote to close the gun show loophole. As the GOP presidential nominee in 2008, McCain earned scorn for his moderate gun control positions.

Responding to the tragic shooting in Colorado during an appearance on Fox News Sunday, Sen. Ron Johnson (R-WI) said he would oppose gun control efforts that could be used to “restrict our freedoms” and instead suggested arming “responsible” people to combat “sick, demented individuals who want to do harm.”

Johnson also argued that any additional measures to restrict large gun magazines that carry 100 rounds of ammunition — similar to the high-capacity clip that the alleged Colorado shooter employed — would infringe on Americans’ Second Amendment rights:

JOHNSON: People will talk about unusually lethal weapons, that could be potentially a discussion you could have. But the fact of the matter is there are 30-round magazines that are just common. You simply can’t keep these weapons out of the hands of sick, demented individuals who want to do harm. And when you try to do it, you restrict our freedoms.

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Johnson’s statement was in direct opposition to Sen. Dianne Feinstein (D-CA), who came on the program to call for a renewed assault weapons ban. “I believe people use these weapons because they can get them,” she said. “I believe that a revolver, a rifle, a hand gun isn’t going to do the damage. It’s the big clips, a hundred rounds. You can’t get to him to dislodge the gun because he can fire so rapidly and has so many bullets.”

Johnson disagreed and argued that the assault weapons ban, which expired in 2004 and banned high-capacity magazines, actually made things worse in the Aurora shooting. “If a responsible individual had been carrying a weapon, maybe, maybe they could have prevented some of those deaths, some of those injuries,” he said.