When 20-year-old Adam Lanza entered Sandy Hook Elementary School in Newtown, Conn., six months ago, armed with a Bushmaster rifle and two handguns, many thought the subsequent massacre would force substantial nationwide changes to American gun laws.

But results have been mixed, with some states tightening laws, some actually expanding gun rights, and federal initiatives being soundly defeated after the massacre that left 20 children and six educators dead.

"I just haven't been surprised. It's exactly what I expected — that there will be a lot of noise and in the end little or nothing would happen," said George Mason University law professor Nelson Lund, an expert on the Second Amendment and who six months ago predicted that little would change.

Back in December, on the day of the shootings, U.S. President Barack Obama hinted that some kind of change to gun laws would be forthcoming. In an emotional statement, Obama pledged that "we’re going to have to come together and take meaningful action to prevent more tragedies like this, regardless of the politics."

He followed up on that pledge by making gun control one of his main priorities for his second term of office. While the issue had barely registered during the presidential campaign, Obama began a determined push for a number of gun control proposals, including the reinstatement of a ban on assault-style rifles and the expansion of federal background checks on firearms buyers.

Of all his initiatives, those expanded background checks seemed to have the most support, with polls at the time showing nearly 90 per cent of Americans in favour of such a move.

Legislation failed in Senate

But when the legislation came to the Senate in April, it failed to get the 60 votes needed and all Obama's major initiatives, including the background checks, were defeated and have remained stalled ever since.

Attitudes in the debate over gun rights versus gun control also seem to be settling back to those that existed before the shooting. The Pew Research Center found that in the days after the school shooting, more people prioritized gun control over gun rights (49 per cent to 42 per cent). But now the public seems evenly divided (50 to 48).

However some gun control advocates say that progress to toughen gun laws is being made.

In an op-ed Friday for the Los Angeles Times, Robyn Thomas and Juleit Leftwich, the executive director and legal director of the Law Center to Prevent Gun Violence, say that gun control is making headway state by state.

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People gather during a ceremony on the six-month anniversary honouring the 20 children and six adults gunned down at Sandy Hook Elementary school on Dec. 14, 2012, in Newtown, Conn. Newtown held a moment of silence Friday for the victims of the massacre. (Jessica Hill/Associated Press)

"Since the Newtown tragedy, gun regulation has made enormous gains in states across the country, with more on the horizon," they write. "In fact, an unprecedented number of gun control laws have been introduced, debated, voted on and enacted this year. What a difference Sandy Hook and six months have made."

Thomas and Letwich write that since the massacre, six states have strengthened their firearms laws, including Connecticut, Maryland and New York, which have beefed up background checks and limited the sale or transfer of military-style assault weapons and large-capacity ammunition magazines.

Delaware and Colorado, they noted, also passed laws requiring background checks on all gun sales and California beefed up its law to confiscate guns from criminals and the mentally ill.

Only 'marginal' changes

But Lund said the changes that have occurred in those states seem to be relatively minor and in states that already have aggressive gun control laws.

"They've made them a little bit more aggressive but I'm not aware of anything really significant that's been done anywhere," he said.

In Connecticut, for example, the state in which the shooting took place, Lund said they "did toughen things up but it's very much at the margin."

"They adjusted their definition of a so-called assault weapon but not in any way that was very significant," he said. "They toughened up some of the penalties and that sort of thing but it looks more like a 'let's send a message' [public relations] stunt than anything else."

In some cases where the population is more supportive of gun rights they've actually expanded gun rights, he said. In fact, a survey by the Wall Street Journal back in April found that in the aftermath of the Newtown tragedy, almost twice as many states had passed laws to weaken gun laws rather than tighten them.

Lund said he believes Obama's gun control measures failed because ultimately too many people in Congress, including the Senate, believe support for gun control will turn out to be a political loser for them.

Pew seems to back up that claim. It found that among those who prioritize gun rights, 41 per cent say they would not vote for a candidate with whom they disagreed on gun policy, even if they agreed with the candidate on most other issues. In comparison, fewer gun control supporters (31 per cent) say gun policy is a make-or-break voting issue for them, Pew found.

"A lot of times these bills are considered in Congress and they sound great in concept but if you really look at them carefully, you can  see when it actually becomes law and put into effect, a lot of your constituents are going to be quite unhappy."

Case in point, the background check proposal, which seemed to have tremendous support.

"When people do polls, they basically poll them on a general concept. And expanded background checks sounds like something harmless to most people," Lund said. "Well there's a big difference between a general concept and a bill with legislative language in it.

"If Congress passes a law that says you can't sell your shotgun to your neighbour who you've known for 30 years without going though some expensive and time-consuming bureaucratic process, you're liable to get upset."

With files from The Associated Press