A group of 16 Republicans in the U.S. Senate last week fired off a letter to federal regulators seeking answers on the growing fuzziness over pistol stabilizing braces. 

The letter, signed by U.S. Sen. Chuck Grassley-- the Senate's president pro tempore-- along with U.S. Sen. Ted Cruz, who sits on the Senate Judiciary Committee, seeks to review all of the Bureau of Alcohol, Tobacco, Firearms and Explosives' internal publications, "instructions, directives, or guidance" on pistol braces by Dec. 7. The information requested specifically asks the agency to shed light on how it makes the determination of whether a firearm is a pistol equipped with a stabilizing arm brace or an NFA firearm, such as a short-barreled rifle (SBR) or a short-barreled shotgun (SBS) including "length of pull" guidelines. 

“ATF has a responsibility to clearly and distinctly articulate its position, in order to inform the public of changing regulations as soon as possible," reads the letter, penned to ATF Acting Director Regina Lombardo and U.S. Attorney General William Barr. "A ‘know-it-when-you-see-it’ approach to firearms by the ATF can quickly become a slippery slope for all legal American gun owners as well as government firearm regulation enforcement.”

The ATF has waffled back and forth on the use and certification of stabilizing braces since 2012, going back to the original SB Tactical "Sig Arm Brace." Long a target of anti-gun groups, some have argued that the ATF could undertake a rulemaking action to outlaw or further regulate braces, of which as many as 4 million could be in circulation. Meanwhile, Democrats on Capitol Hill have included braces in their "forbidden" list in planned federal "assault weapon" bans.

This year has already seen the ATF go after Q over that company's Honey Badger pistol, equipped with an SB Tactical brace. 

The Senate letter follows in the wake of a previous effort earlier this year by House Republicans who warned federal firearms regulators to slow their roll when it comes to what could be a ban on some of the popular accessories.

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