WASHINGTON (Reuters) - U.S. firearms makers will be able within days to export as much as 20% more guns, including assault rifles and ammunition, under rules the Trump administration announced on Friday.

The change, which had been contemplated for more than a decade, will officially move oversight of commercial firearm exports from the State Department to the Commerce Department, where export licenses will be much easier to obtain.

The move here by President Donald Trump's administration will generate business for gun makers such as American Outdoor Brands Corp AOBC.O and Sturm Ruger & Co RGR.N, while increasing the sale of weapons abroad. Relaxing the rules could increase foreign gun sales by as much as 20%, the National Shooting Sports Foundation has estimated.

The Department of Commerce is “better oriented for the kinds of licensing requirements that we are going to be enforcing.” Rich Ashooh, the U.S. Assistant Secretary of Commerce for Export Administration told reporters in a conference call.

A draft of the rules was published on Friday, with publication in the Federal Register expected next week, said Clarke Cooper the State Department’s Assistant Secretary for Political-Military Affairs.

“While we are providing industry a some regulatory relief and a cost savings, it does improve enforceability,” Cooper said.

U.S. Senator Bob Menendez (D-N.J.), Ranking Member of the Senate Foreign Relations Committee, said the administration “is choosing a path that puts the gun industry’s profits ahead of the safety of families.” The guns “are easily modified, diverted, and proliferated, and are the primary means of injury, death, and destruction in civil and military conflicts throughout the world.”

U.S. Representative Ted Lieu, a California Democrat, called the move “bad,” at Tuesday’s Forum on the Arms Trade Annual Conference, in comments that echoed arms control advocates. Under the change, Lieu said, more weapons will be sold overseas and “give Congress even less authority as a check and balance on those sales.”

Under the new rule, 3D printed guns will still be regulated. “This control will help ensure that U.S. national security and foreign policy interests are not undermined by foreign persons’ access to firearms production technology,” a version of the rule posted on the Federal Register said.

Reuters first reported on the Trump administration's interest in the oversight shift in 2017 here. The action is part of a broader Trump administration overhaul of weapons export policy here.