Democratic  presidential candidates Hillary Clinton and Bernie Sanders speak simultaneously at the fourth Democratic presidential candidates debate in Charleston. (Randall Hill/Reuters)

One of the most significant flashpoints from Sunday's fourth Democratic presidential campaign came when the discussion turned to gun safety legislation, an issue area where which former secretary of state Hillary Clinton has repeatedly criticized Sen. Bernie Sanders (Vt.).

“I have made it clear based on Senator Sanders's own record that he has voted with the NRA, with the gun lobby numerous times,” Clinton said in one of her most direct attacks of the night.

Namely, Clinton knocked Sanders’ votes against the Brady Bill, his support for legislation that allows individuals to purchase guns after a waiting period even if a background check has not been completed (now known as the “Charleston loophole”), and votes in favor of immunity provisions for the gun industry.

Watch snippets from exchange here:

At a debate in Charleston, S.C., Democratic presidential candidates Hillary Clinton, Bernie Sanders and Martin O'Malley sparred over their respective records on gun control on Jan. 17. (NBC/YouTube)

Sanders, who represents rural Vermont, was clearly not pleased.

“I think Secretary Clinton knows that what she says is very disingenuous. I have a D-minus voting record from the NRA,” Sanders responded. “I have supported from day one an  instant background check to make certain that people who should not have guns do not have guns. And that includes people of criminal backgrounds, people who are mentally unstable.”

There were plenty of accusations thrown around as the two tussled, and it was easy to miss the specifics. To help sort it out, below is an abridged version of The Fact Checker's excellent rundown on Sanders’s record:

“Sanders voted repeatedly against the Brady bill, which in its original version had a 10-day waiting period. But he did vote for an NRA-backed amendment, sponsored by then-Rep. George Gekas (R-Pa.), that altered the Brady bill to require instant criminal background checks five years after enactment, even though the technology did not exist at the time. The waiting period would sunset within five years, once the system was expected to be operational.

Until passage of the amendment, the Brady bill at that point had a seven-day waiting period. But the amendment — pushed by a lawmaker close to the NRA — requiring the instant background system also cut the processing time to just 24 hours if the instant background system didn’t come back with an answer.

Later, after negotiations between the Senate and the House, the final version of the Brady bill emerged with a three-day period to allow law-enforcement officials to process the information.”

Clinton's statements, in short, pass the muster. Fact checkers at several media organizations have come to similar conclusions.

Sanders also defended himself against the accusation that he has voted to give immunity to gun manufacturers, clarifying that he is in favor of stronger provisions than currently exist but making clear that he does see important limitations to expanding liability. That is is a shift for Sanders, who has previously expressed misgivings about holding manufacturers accountable.

“What I have said is that gun manufacturer's liability bill has some good provisions among other things,” he said, but “a small mom-and-pop gun shop who sells a gun legally to somebody should not be held liable if somebody does something terrible with that gun,” Sanders said.

“So what I said is I would re-look at it. We are going to re-look at it and I will support stronger provisions,” he added.

Read more:

[Hillary Clinton’s claim that Bernie Sanders voted for the ‘Charleston loophole’ checks out.]

[Clinton: Sanders ‘consistently refusing’ to repeal gun manufacturer liability law.]

[Bernie Sanders, the Brady bill and ‘instant’ background checks]