Receiver (firearms)#In U.S. law
{{Short description|Firearm component that houses the operating parts of the weapon}}
File:Disassembled mauser long action.jpg action showing a partially disassembled receiver and bolt]]
In firearms terminology and law, the firearm frame or receiver is the part of a firearm which integrates other components by providing housing for internal action components such as the hammer, bolt or breechblock, firing pin and extractor, and has threaded interfaces for externally attaching ("receiving") components such as the barrel, stock, trigger mechanism and iron/optical sights.{{cite web|title=27 CFR 478.11: Meaning of terms| quote=Firearm frame or receiver. That part of a firearm which provides housing for the hammer, bolt or breechblock, and firing mechanism, and which is usually threaded at its forward portion to receive the barrel. |url=http://www.ecfr.gov/|access-date=16 September 2016|work=US Government|date=2016}} Some firearm designs, such as the AR-15 platform, feature receivers that have 2 separate sub-assemblies called the upper receiver which houses the barrel/trunnion, bolt components etc and the lower receiver (Trigger Mechanism Housing in some cases) that holds the fire control group, pistol grip, selector, stock etc.Royal Air Force Common Core and Deployment Skills Aide-Memoire AP 3242B VOL 5, ABBREVIATIONS
The receiver is often made of forged, machined, or stamped steel or aluminium. Apart from these traditional materials, modern techniques have introduced polymer and sintered metal powder receivers to the market.{{cite web |url=http://world.guns.ru/assault/as75-e.htm |title=HK416 modular assault rifle / carbine / upper receiver assembly (Germany) |access-date=5 Aug 2010 }}
Mounting
A barrel may typically be affixed to a firearm receiver using barrel and receiver action threads or similar methods.
In US law
{{See also|Parts kit}}
File:Stag2wi.jpg rifles showing their configurations with different upper receivers. The lower receiver is visible at the bottom]]
For the purposes of United States law, the receiver or frame is legally the firearm,{{cite web |url=http://www.atf.gov/firearms/faq/firearms-technology.html|title=Firearms - Frequently Asked Questions - Firearms Technology {{!}} ATF|access-date=7 June 2015 |archive-url=https://web.archive.org/web/20150503044932/https://www.atf.gov/firearms/faq/firearms-technology.html |archive-date=3 May 2015 }} and as such it is the controlled part. The definition of which assembly is the legal receiver varies from firearm to firearm, under US law. Generally, the law requires licensed manufacturers and importers to mark the designated receiver with a serial number, the manufacturer or importer, the model and caliber. Makers of receivers are restricted by International Traffic in Arms Regulations. Thus, in the case of a firearm that has multiple receiver parts, such as the AR-15, which has an upper and a lower receiver, the legally controlled part is the one that is serialized.
For the AR-15 rifle, the lower receiver assembly is legally considered the actual receiver,{{cite book|last=Muramatsu|first=Kevin|editor=Jerry Lee|title=Gun Digest 2016|chapter-url=https://archive.org/details/gundigest20160000unse/page/41/|year=2015|publisher=F+W Media, Inc.|location=Iola, Wisconsin|isbn=978-1-4402-4430-8|page=41|chapter=The State of the AR Industry}} although it is functionally a chassis that also houses the separate trigger group. In the FN-FAL rifle, it is the upper assembly that is serialized and legally considered the receiver.{{cite book|last1=Jenzen-Jones|first1=N.R.|last2=Spleeters|first2=Damien|title=Identifying & Tracing the FN Herstal FAL Rifle: Documenting signs of diversion in Syria and beyond|url=https://books.google.com/books?id=MG53CgAAQBAJ&pg=PA16|date=31 August 2015|publisher=Armament Research Services Pty. Ltd.|isbn=978-0-9924624-6-8|page=16|location=Australia}}{{cite web|title=27 CFR 478.11: DEFINITION OF FIREARM FRAME OR RECEIVER|url=https://www.atf.gov/file/55436/download|access-date=16 September 2016|work=ATF|date=2008}} This has led to prosecutors dropping charges against illegal manufacturing of AR-type firearms to avoid court precedents establishing that neither the upper nor the lower receiver individually contain all the components to be legally classified as a firearm.{{Cite web|author=Scott Glover|title=He sold illegal AR-15s. Feds agreed to let him go free to avoid hurting gun control efforts|url=https://www.cnn.com/2019/10/11/us/ar-15-guns-law-atf-invs/index.html|access-date=2021-04-30|website=CNN|date=11 October 2019}}
=Unfinished receivers=
"Unfinished receivers", also called "80 percent receivers" or "blanks", are partially completed receivers with no serial numbers. Purchasers must perform their own finishing work in order to make the receiver usable. The finishing of receivers for sale or distribution by unlicensed persons is against US law.{{cite news|last1=Horwitz|first1=Sari|title='Unfinished receivers,' a gun part that is sold separately, lets some get around the law|url=https://www.washingtonpost.com/world/national-security/unfinished-receivers-that-can-be-used-to-build-guns-pose-problems-for-law-enforcement/2014/05/13/8ec39e9e-da51-11e3-bda1-9b46b2066796_story.html|access-date=5 September 2016|newspaper=Washington Post|date=May 13, 2014}} Because an unfinished 80% receiver is not a firearm, purchasers do not need to pass a background check. The resulting firearm is known as a "ghost gun".{{cite news|last1=Stanton|first1=Sam|last2=Walsh|first2=Denny|title=California black market surges for 'ghost guns'|url=http://www.sacbee.com/news/local/crime/article50685560.html|access-date=5 September 2016|work=Sacramento Bee|date=December 19, 2015}}
During the Biden Administration, the ATF imposed regulations on the sale and marketing of unfinished receivers and kits containing them by revising the legal definition of receivers to include "a partially complete, disassembled, or nonfunctional frame or receiver, including a frame or receiver parts kit, that is designed to or may readily be completed, assembled, restored, or otherwise converted to function as a frame or receiver". (The term "receiver" was also redefined as referring to non-handgun firearms, while "frame" was redefined as referring to handguns exclusively.) The new definitions went into effect on August 24, 2022.{{Federal Register|87|24652}} In the case VanDerStok v. Garland, filed on June 30, 2023, a federal court in Texas ruled that the new ATF regulations exceeded the agency's statutory authority, and struck them down.{{cite court |litigants=VanDerStok v. Garland |court=US District Court for the Northern District of Texas |date=2022-08-11 |url=https://storage.courtlistener.com/recap/gov.uscourts.txnd.366145/gov.uscourts.txnd.366145.227.0.pdf |quote=This case presents the question of whether the federal government may lawfully regulate partially manufactured firearm components, related firearm products, and other tools and materials in keeping with the Gun Control Act of 1968. Because the Court concludes that the government cannot regulate those items without violating federal law, the Court holds that the government’s recently enacted Final Rule, Definition of “Frame or Receiver” and Identification of Firearms, 87 Fed. Reg. 24,652 (codified at 27 C.F.R. pts. 447, 478, and 479), is unlawful agency action taken in excess of the ATF’s statutory jurisdiction. On this basis, the Court vacates the Final Rule.}} However, on August 8, 2023, the Texas court's nationwide vacatur was temporarily placed on hold by the Supreme Court of the United States, leaving the new ATF regulations on unfinished receivers in place.{{cite web |url=https://www.nytimes.com/2023/08/08/us/supreme-court-biden-ghost-guns.html |title=By 5-4 Vote, Supreme Court Revives Biden's Regulation of 'Ghost Guns' |last=Liptak |first=Adam |date=2023-08-08 |website=The New York Times |url-status=live |archive-url=https://web.archive.org/web/20230829054951/https://www.nytimes.com/2023/08/08/us/supreme-court-biden-ghost-guns.html |archive-date=2023-08-29 |language=en |access-date=2023-08-30}}
3D printed receivers
{{As of|2024}}, several designs and at least two designs for 3D printable polymer lower unfinished receivers for the AR-15 have been released: the AR Lower V5 and the Charon. 3D printed designs may also be used to produce privately made firearms.{{cite magazine |title = I Made an Untraceable AR-15 Ghost Gun in My Office And It Was Easy |first1 = Andy |last1 = Greenberg |magazine = Wired |date = June 3, 2015 |url = https://www.wired.com/2015/06/i-made-an-untraceable-ar-15-ghost-gun/ |accessdate = October 17, 2016 |url-status = live |archiveurl = https://web.archive.org/web/20161020040839/https://www.wired.com/2015/06/i-made-an-untraceable-ar-15-ghost-gun/ |archivedate = October 20, 2016 |df = mdy-all}}
In Canadian law
{{See also|Firearms regulation in Canada#Classifications}}
The receiver or frame is legally the firearm, and as such it is the part that requires a manufacturer's serial number and valid Possession and Acquisition Licence to acquire and own. In the case of a handgun frame or revolver frame, it is the part that requires a Restricted-class PAL (RPAL), and registration.