President Obama is taking executive action this week on guns. He will make the announcement from the East Room tomorrow, and follow up with a nationally televised town hall meeting on CNN Thursday evening.

Heads will explode, and likely already are. But unlike executive orders, executive actions are more difficult to unwind. They are regulations, policies set by government agencies, and more.

Here's the summary:

Background checks:

• The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) is making clear that it doesn’t matter where you conduct your business—from a store, at gun shows, or over the Internet: If you’re in the business of selling firearms, you must get a license and conduct background checks.
• ATF is finalizing a rule to require background checks for people trying to buy some of the most dangerous weapons and other items through a trust, corporation, or other legal entity.
• Attorney General Loretta E. Lynch has sent a letter to States highlighting the importance of receiving complete criminal history records and criminal dispositions, information on persons disqualified because of a mental illness, and qualifying crimes of domestic violence.
• The Federal Bureau of Investigation (FBI) is overhauling the background check system to make it more effective and efficient. The envisioned improvements include processing background checks 24 hours a day, 7 days a week, and improving notification of local authorities when certain prohibited persons unlawfully attempt to buy a gun. The FBI will hire more than 230 additional examiners and other staff to help process these background checks.

Local enforcement:

• The Attorney General convened a call with U.S. Attorneys around the country to direct federal prosecutors to continue to focus on smart and effective enforcement of our gun laws.
• The President’s FY2017 budget will include funding for 200 new ATF agents and investigators to help enforce our gun laws.
• ATF has established an Internet Investigation Center to track illegal online firearms trafficking and is dedicating $4 million and additional personnel to enhance the National Integrated Ballistics Information Network.
• ATF is finalizing a rule to ensure that dealers who ship firearms notify law enforcement if their guns are lost or stolen in transit.
• The Attorney General issued a memo encouraging every U.S. Attorney’s Office to renew domestic violence outreach efforts.

Mental health services:

• The Administration is proposing a new $500 million investment to increase access to mental health care.
• The Social Security Administration has indicated that it will begin the rulemaking process to include information in the background check system about beneficiaries who are prohibited from possessing a firearm for mental health reasons.
• The Department of Health and Human Services is finalizing a rule to remove unnecessary legal barriers preventing States from reporting relevant information about people prohibited from possessing a gun for specific mental health reasons.

Advancing gun safety technology:

• The President has directed the Departments of Defense, Justice, and Homeland Security to conduct or sponsor research into gun safety technology
• The President has also directed the departments to review the availability of smart gun technology on a regular basis, and to explore potential ways to further its use and development to more broadly improve gun safety.

These measures aren't as robust as an act of Congress could be. We could ban some of the most destructive weapons and keep them out of the hands of mass killers if we didn't have a Congress so intent on sleeping with the NRA instead of doing their duty. But they are the kinds of things the President can do to maybe prevent even one mass shooting from happening.