The memo says requiring background checks for more gun purchases could help, but also could lead to more illicit weapons sales. It says banning assault weapons and high capacity ammunition magazines produced in the future but exempting those already owned by the public, as Obama has proposed, would have limited impact because people now own so many of those items.
It also says that even total elimination of assault weapons would have little overall effect on gun killings because assault weapons account for a limited proportion of those crimes.
The nine-page document says the success of universal background checks would depend in part on "requiring gun registration," and says gun buybacks would not be effective "unless massive and coupled with a ban."
The administration has not proposed gun registration, buybacks or banning all firearms. But gun registration and ownership curbs are hot-button issues for the NRA and other gun-rights groups, which strenuously oppose the ideas.
Justice Department and White House officials declined to provide much information about the memo or answer questions about it on the record.
The memo has the look of a preliminary document and calls itself "a cursory summary" and assessment of gun curb initiatives. The administration has not released it officially. But the NRA has posted the memo on one of its websites and cites it in advertising aimed at whipping up opposition to Obama's efforts to contain gun violence. The ad says the paper shows that the administration "believes that a gun ban will not work without mandatory gun confiscation" and thinks universal background checks "won't work without requiring national gun registration" - ideas the president has not proposed or expressed support for.
While the memo's analysis of gun curb proposals presents no new findings, it is unusual for a federal agency document to surface that raises questions about a president's plans during debate on a high-profile issue.
The NRA's chief Washington lobbyist, Chris W. Cox, declined to say how his organization obtained the memo. He said the commercial is running online in 15 states.
The memo was written under the name of Greg Ridgeway, acting director of the National Institute of Justice, the Justice Department's research arm. Department officials said Ridgeway was not granting interviews.