Senate Democrats encouraged the Department of Justice and the Bureau of Alcohol, Tobacco, Firearms, and Explosives to better enforce the “Ghost Gun Rule” in a letter Tuesday.

Signed by 14 Senate Democrats, the letter urges the DOJ and ATF to see that the “Ghost Gun Rule,” which cracks down on the selling of ghost guns, is “enforced strongly,” as companies have found loopholes to continue selling them.

What are ghost guns?

Ghost guns are homemade guns that don’t have a serial number, making them untraceable.

Guns that are built from kits, other parts or are 3-D printed are considered ghost guns, and are not regulated the same way other firearms are.

What is the ‘Ghost Gun Rule’?

In April, President Joe Biden announced a new rule to regulate ghost guns, the Deseret News reported.

The rule, which requires homemade firearm kits be assigned serial numbers and buyers to undergo a background check, went into effect in August.

How gun dealers are getting around the ‘Ghost Gun Rule’

But companies have found a loophole. The rules are being strictly enforced for complete gun kits, but not for nearly-complete frames and receivers, according to The Hill.

Essentially, the companies selling these kits are claiming that the rules do not apply if they sell the gun in parts.

In the letter sent to the DOJ and ATF, Senate Democrats said if they did not enforce the “Ghost Gun Rule” for nearly-complete frames and receivers, it would be a “colossal loophole that would swallow the rule.”

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“The outcome is one and the same,” the letter states. “Both kits and standalone frames and receivers can readily be completed, assembled, restored or otherwise converted to an operational frame or receiver.”

On Wednesday, House Democrats sent a similar letter to Biden, Attorney General Merrick Garland and ATF Director Steve Dettelbach, urging them to enforce the rule when it comes to the selling of nearly-complete frames and receivers.

“These parts are a grave danger to public safety and must be regulated, whether they are sold alone or as part of a kit or with tools or instructions needed to finish the firearm,” the letter states.