"You know you need to dig into a politician's record to find out where they really stand. You know some will change their position or have little record for you to judge. That is not the case with me," he said.
In another swipe at Giuliani, McCain reminded the NRA crowd that he'd voted for a congressional bill that banned lawsuits against gun manufacturers that would hold them accountable for gun-related crimes.
"This was a particularly devious effort to use lawsuits to bankrupt our great gun manufacturers," McCain said. "A number of big-city mayors decided it was more important to blame the manufacturers of a legal product than it was to control crime in their own cities. Fortunately, we are able to protect manufacturers from these frivolous lawsuits."
McCain delivered another swipe at Romney, who, in an effort to brandish his gun credentials, once said he hunted "small varmints."
"There is the hunting myth," McCain said, "if you show your bona fides by hunting ducks or varmints or quail, it makes up for support for gun control. This myth overlooks a fundamental truth: The Second Amendment is not about hunting, it is about freedom."
Romney has also been accused of changing his position on gun control, buying his first NRA membership last August.
During the time he was governor of Massachusetts, Romney pledged to uphold the state's gun control laws. He has previously supported a ban on some assault weapons and federal waiting periods before gun purchases.
More recently, Romney told a man wearing a NRA cap in New Hampshire, "I purchased a gun when I was a young man. I've been a hunter pretty much all my life."
It was later reported that Romney had only been on two hunting trips, prompting the candidate to explain, "I'm by no means a big game hunter. I'm more Jed Clampett than Teddy Roosevelt," he said at the time.
Romney delivered his NRA message via video.
"I support the Second Amendment as one of the most basic and fundamental rights of every American. It's essential to our functioning as a free society, as are all the liberties enumerated in the Bill of Rights," Romney said on the video. "I'd be proud to have your support again as I campaign for president."
Romney took a swipe of his own at McCain's support for campaign finance reform. The NRA has long railed against McCain's attempts to reform for campaign finance laws believing it encroaches on their ability to financially support the pro-gun rights candidates they endorse.
"As president ... I'll ask Congress to repeal the McCain-Feingold law, which sought to impose restrictions on the First Amendment rights of groups like the NRA to advocate for issues we care about. Some parts have already been declared unconstitutional. We ought to get rid of the entire bill," Romney said.
During the 2008 election campaign, Romney has been accused of flip-flopping on gun rights. During the time he was governor of Massachusetts, Romney pledged to uphold the state's gun control laws. He has previously supported a ban on some assault weapons and federal waiting periods before gun purchases.
In an effort to boost Romney's gun rights credentials, the campaign announced early Friday that a former NRA director of general operations, Craig Sandler, endorsed the governor's '08 bid.