There's a fair bit to digest in President Obama's new proposals for reducing gun violence. They include everything from renewing the assault-weapons ban to more mental-health funding for schools, as well as 23 different executive actions.

A lot of guns, a lot of proposals. (AP)

So which of his proposals might have the most meaningful impact on gun violence? And which policy ideas could prove ineffective? We asked a number of gun and crime experts for their thoughts on different aspects of Obama's proposals today. Here are five points that stuck out (although note that this is hardly a comprehensive list):

1) Universal background checks could, potentially, have a large impact on gun crime. At the moment, only licensed gun dealers have to run background checks on prospective buyers. There's no such requirement for private sales between individuals. According to Jens Ludwig of the University of Chicago, surveys have found that nearly 80 percent of guns used in crimes are obtained on this secondary market.

"Anything that can add friction to that secondary market could prove very helpful," Ludwig said. He does note, however, that a lot will depend on how well this rule is enforced. (For more detail on how universal background checks might work, see this earlier post.)

2) Giving federal law enforcement more power to trace guns could also matter a lot. At the moment, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) has a limited ability to share its data on where guns actually come from — and it can't keep computerized records. What's more, not all federal agencies are required to trace all guns they've recovered. One of Obama's executive orders focuses on requiring these traces.

Doing so could help crack down on key sources of crime guns, says Mark Kleiman, a crime specialist at UCLA. "The places where bad guys get guns are very concentrated," he said. "Some of these places are private markets, some are scofflaw gun stores. Better tracing can show us where those spots are. When a single store has supplied 200 crime guns, we ought to be able to act on that." However, Kleiman notes that Obama can't alter the limitations on tracing entirely through executive order — Congress will need to help.

3) Few of the proposals would do much to help with the problem of stolen guns. "About a million guns are stolen each year," said Yale's John Donohue. "Shutting off the spigot on the purchase end is helpful, but it does not solve the problem that some gun owners are completely irresponsible in how they allow access to their guns to criminals."

Donohue, for his part, suggests that Congress should go further by requiring mandatory gun insurance for everyone who owns a firearm: "If you had some kind of mandatory insurance scheme that made people liable when their guns are used in other shootings, the insurance companies would start to police this, to pressure people to buy guns that have some kind of fingerprint capacity" — or guns that can only be used by their owners. "Other countries are much more attentive about that."

4) Experts tend to be more skeptical about the assault-weapons ban. Obama is asking Congress to "reinstate and strengthen" the ban on assault weapons and high-capacity magazines that was in effect from 1994 to 2004. Research has found that the previous ban was fairly easily circumvented — in part because it's difficult to define what an "assault weapon" actually is, and in part because there are millions of such weapons already in circulation. A University of Pennsylvania study of the previous ban found that it led to "no discernible reduction in the lethality and injuriousness of gun violence.”

It's true that Australia managed to pass a sweeping ban on all semi-automatic long guns that reduced shootings in that country. But it's unlikely that a bill like that could get through Congress (or the Supreme Court). Note that even a water-down assault-weapons ban is likely to face resistance from lawmakers.  "Is it something that can pass the Senate? Maybe," said Senate Majority Leader Harry Reid recently. "Is it something that can pass the House? I doubt it."

5) Obama wants to lift a restriction on federal funding for gun research, but that might be only partially effective. In 1996, Congress passed a law that prohibited federal funding for research that "advocates or promotes gun control.” That law was so vague that it essentially put a freeze on all research on guns and gun violence, researchers say. In an executive order Wednesday, Obama clarified that the Centers on Disease Control should go forward with research on "causes and prevention of gun violence." In other words, stop being so timid. Conduct research on anything that's not expressly forbidden.

But, explains Andrew Rosenberg of the Union of Concerned Scientists, this new executive order isn't likely to resolve the issue completely: "The White House is making the right move in pushing for more gun violence research. But now scientists will have one interpretation of the law from the executive branch and another from Congress." Until Congress repeals its law, he says, gun research is likely to proceed only haltingly. And that will make it even more difficult to tell which measures are effective and which aren't.

Dylan Matthews contributed reporting for this post.

Further reading:

--In earlier posts we took closer looks at the 1994 assault-weapons ban, at the idea of universal background checks, and at Obama's mental-health proposals. We've also scrutinized proposals for putting more security guards in schools, which Obama endorsed today.

--My colleague Aaron Blake looks at which of Obama's gun proposals are likely to pass Congress.

--My colleague Ezra Klein has argued that gun policies should focus primarily on reducing gun homicides, rather than on preventing (horrible but rare) mass shootings like Newtown.

--Over at his blog, UCLA's Mark Kleiman has further thoughts on the gun proposals.