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A Fire Control Unit – What Does ATF Rule 2021R-05F State?

Does the ATF consider a Fire Control Unit a “Frame” or a “Receiver”?

In June, 2021 the ATF rule 2021R-05F was proposed to the public. We immediately began receiving calls from clients asking us how to add a new ATF Type to their Easy Bound Book. They also wanted to know how to determine if a Firearm Control Unit is a Frame or Receiver. We were glad they made the call because by calling us they saved themselves from misidentifying a firearm in their records. Misidentifications can have serious ramifications and are usually found during ATF audits.

Do you know what the correct ATF Type for the Sig Sauer P320 Fire Control Unit is?

A. Fire Control Unit
B. Firearm
C. Frame
D. Receiver

The correct answer is C. Why? Prior to August 2022, it could have been a Frame or Receiver however, 2021R-05F says Frames are for Pistols or Revolvers, Receivers are for Rifles or Shotguns.

Read on as we share what the ATF states in the new multi-component firearms ruling.

Sig Sauer P320

ATF Rule 2021R-05 – Excerpt

The Department of Justice (“Department”) is amending Bureau of Alcohol, Tobacco, Firearms, and Explosives (“ATF”) regulations to remove and replace the regulatory definitions of “firearm frame or receiver” and “frame or receiver” because the current regulations fail to capture the full meaning of those terms.

The Department is also amending ATF’s definitions of “firearm” and “gunsmith” to clarify the meaning of those terms, and to provide definitions of terms such as “complete weapon,” “complete muffler or silencer device,” “multi-piece frame or receiver,” “privately made firearm,” and “readily” for purposes of clarity given advancements in firearms technology.

Further, the Department is amending ATF’s regulations on marking and recordkeeping that are necessary to implement these new or amended definitions.

Federal Register :: Definition of “Frame or Receiver” and Identification of Firearms

ATF Firearm Types

It’s Important You Know the Difference

One of the many updates we made was to remove the ability to “Add or Edit ATF Firearm Types” in your records. We progressively rolled out this update since January 2021. It is part of our ongoing effort to help you maintain your ATF compliance. 

Again, by calling us first, our clients saved themselves from misidentifying a firearm on an entry in their Easy Bound Book records.

As your expert in the highly regulated firearms industry, we are here to help you. Contact us first, we have your best interest and business in mind.

If you would like more information on ATF ruling 2021R-05F, check out the links below.

Summary of Final Rule 2021R-05 | Bureau of Alcohol, Tobacco, Firearms and Explosives (

Definition of “Frame or Receiver” and Identification of Firearms | Bureau of Alcohol, Tobacco, Firearms and Explosives (

Final Rule – 2021R-05F | Q&A Bureau of alcohol, tobacco, Firearms and Explosives (

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