The U.S. Senate Committee on the Judiciary heard witness testimonies Tuesday, on a proposed rule from the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) that would change the definition of a receiver on a gun. 

The idea is that homemade guns using part kits are not traceable since there is no serialization. Receivers are the only part that requires a background check for purchase and, consequently, have a serial number. 

Currently, a receiver is defined as the part of the firearm which holds all the parts to make it function. The proposed rule would change the definition to any externally visible housing or holding structure. Some testified that this proposed serialization would help law enforcement trace criminals of gun violence. 

Ashley Hlebensky, former curator of the Cody Firearms Museum, testified at the hearing, saying that expanding definitions could have negative repercussions as they are complicated and confusing. 

“These things can affect both sides, criminalizing those who otherwise would be innocent but also opening the door for loopholes and litigation and worse of all continued violence,” testified Hlebinsky.

The proposal is open for public comment.