Judicial Watch, the noted Washington watchdog, is demanding that the Bureau of Alcohol, Tobacco, Firearms and Explosives hand over some 1,900 pages of records regarding a plan to ban ammunition for the popular AR-15 rifle.

For more than three years, Judicial Watch said, the ATF has refused to provide the documents, subject to a Freedom of Information Act request, while admitting it retrieved them.

The organization said it now has filed a brief in federal court in Washington asking for an order to release the records.

The case arose in 2015 when the agency said it was going to reclassify certain ammunition for the AR-15 as "armor-piercing," which would make it unavailable to owners of the weapon.

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Judicial Watch President Tom Fitton charged the ATF is "stonewalling," asserting "the Obama administration attempted to institute gun control stealthily by going after ammunition instead of guns."

Congress also has raised concerns about the proposed ban. More than 200 members have written to the ATF, arguing the ammunition in question has been used for "sporting purposes."

Last year, Judicial Watch filed a lawsuit after the government failed to respond to the earlier FOIA request.

Judicial Watch wanted records "of communications, including emails, to or from employees or officials of the ATF related to the decision to revise the ATF 2014 Regulation Guide to no longer exempt 5.56 mm, SS109 and M855 (i.e.,'green tip' AR-15) ammunition from the definition of 'armor-piercing' ammunition."

"Using a narrow interpretation of the FOIA request and neglecting Judicial Watch's explanation, the ATF has consistently refused to substantively produce documents in this case."

The organization even offered a quick solution: It would file a new request and if the ATF complies, the current court dispute would be over.

"ATF is wrong about what FOIA requires the agency to release in this case," Judicial Watch said. "Under FOIA, defendant agencies must release records reasonably described by a FOIA request to the extent an agency can discern what is being requested. … It is impossible for ATF to still claim it does not know what Judicial Watch is seeking after reading Judicial Watch's opposition brief and response to defendant's statement."