Receiver (firearms)

File:Disassembled mauser long action.jpg

A disassembled Mauser 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.<ref name="Receiver definition">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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.<ref>Royal Air Force Common Core and Deployment Skills Aide-Memoire AP 3242B VOL 5, ABBREVIATIONS</ref>

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.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Mounting

A barrel may typically be affixed to a firearm receiver using barrel and receiver action threads or similar methods.

In US law

File:Stag2wi.jpg

AR-15 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,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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.<ref name="GD2015"/>

For the AR-15 rifle, the lower receiver assembly is legally considered the actual receiver,<ref name="GD2015">Template:Cite book</ref> 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.<ref name="Jenzen-JonesSpleeters2015">Template:Cite book</ref><ref name="ATF Rul. 2008-1">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

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.<ref name="Horwitz">Template:Cite news</ref> Because an unfinished 80% receiver is not a firearm, purchasers do not need to pass a background check.<ref name="Horwitz"/> The resulting firearm is known as a "ghost gun".<ref name="Stanton">Template:Cite news</ref>

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.<ref>Template:Federal Register</ref> 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.<ref>Template:Cite court</ref> 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.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

3D printed receivers

Template:As of, 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.<ref name="Greenberg">Template:Cite magazine</ref>

Name	Date made public	Type	Process	Designer	Caliber
AR Lower V5<ref name="TC600">Template:Cite news ()</ref>	2013-032013, March<ref name="TC600" />	Receiver: AR-15 rifle lower receiver<ref name="TC600" />	FDM<ref name="Printed AR Lower v5 Review">Printed AR Lower v5 Review, Defense Distributed official tumblr blog (archive)</ref>	Defense Distributed<ref name="TC600" />	.223 Rem/ 5.56x45
	The receiver was able to handle enough stress to fire more than 600 rounds.<ref name="TC600" />
Charon<ref name="outdoorhub.com">3D-printed Hybrid AR-15/FN P90 Lower and 12 Gauge Slugs Make Web Debut, outdoorhub, May 22, 2013. (archive)</ref><ref name="guns.com">Slowik, Max, Meet the Charon Family of 3D-Printable AR Lowers (Photos), 3 June 2013.</ref><ref name="Slowik 2013">Slowik, Max, "3D Printing Community Updates Liberator with Rifle, Pepperbox and Glock-Powered ‘Shuty-9′", 1 July 2013.</ref>	2013-05May 2013<ref name="outdoorhub.com" />	Receiver: AR-15 rifle lower receiver<ref name="outdoorhub.com" /><ref name="guns.com" /><ref name="Slowik 2013" />	FDM<ref name="Charon V3">Charon V3, grabcad, September 3, 2013. (archive)</ref>	WarFairy<ref name="guns.com" /><ref name="Slowik 2013" />	.223 Rem/ 5.56x45
	Charon V3 weighs 0.2 pounds and showed no signs of strain after 96 rounds of 5.56 AR-15 ammo were fired.<ref name="Charon V3" />
WarFairy P-15<ref name="outdoorhub.com" />	2013-052013, May<ref name="outdoorhub.com" />	Receiver: AR-15 rifle lower receiver<ref name="TC600" />	FDM<ref name="Charon V3" />	WarFairy<ref name="guns.com" /><ref name="Slowik 2013" />	.223 Rem/ 5.56x45
Hanuman AR-15 Bullpup<ref name="thefirearmblog.com">WarFairy’s 3D Printable AR-15 Bullpup, firearmblog, May 27, 2014. (archive)</ref><ref name="Guns 2014">Check out this 3D-printable bullpup for AR-pattern uppers, Guns.com, May 27, 2014. (archive)</ref>	2014-052014, May<ref name="thefirearmblog.com" /><ref name="Guns 2014" />	Receiver: AR-15 rifle bullpup lower receiver<ref name="thefirearmblog.com" /><ref name="Guns 2014" />	FDM w/ ABS	WarFairy<ref name="thefirearmblog.com" /><ref name="Guns 2014" />	.223 Rem/ 5.56x45
	According to the creators, "It requires a bufferless upper to function, such as the ARAK-21 or Rock River Arms PDS Carbine, or a regular upper with a CMMG Style .22 LR Conversion installed."<ref name="thefirearmblog.com" />
Ruger Charger<ref name="3dprintrugger">3D Printed Semi-automatic Ruger Charger Pistol is Assembled and Fired – ‘If you take my gun, I’ll print another!’, 3Dprint, July 4, 2014. (archive)</ref><ref name="reason">3D-Printed Semiautomatic .22 Debuts. "If you take my gun, I will simply print another one.", Reason, July 2014. (archive)</ref><ref name="ammolandrugger">3D Printed Ruger Style Pistol Demo by Buck O’ Fama ~ Video, Ammoland, July 4, 2014. (archive)</ref>	2014-072014, July<ref name="reason" />	Receiver: Ruger 10/22 semi-automatic pistol<ref name="reason" />	FDM<ref>3D Printing Lets Man Assemble Ruger Charger Pistol Without Legal Paperwork, Softpedia, July 8, 2014. (archive)</ref>	"Buck-o-Fama" (pseudonym)<ref name="reason" />	.22 Long Rifle
	A pistol version of the popular Ruger 10/22 rifle.<ref name="3dprintrugger" /><ref name="reason" />
CM901<ref>Great, now 3D-printed rifles can fire larger, deadlier rounds</ref>	2015-032015, March	Receiver: AR-10 Receiver	FDM	Printed Firearm<ref>Template:In lang 3D Yazıcıdan Üretilen Ölümcül Tüfek!</ref>	7.62×51mm
	Based on Colt CM901.
Lopoint / Bigpoint<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	2019, November (v1); 2020, November (,40/.45); 2021, May (v2)	Frame: Hi-Point pistol frame	FDM	CTRLPew / Atmac / freeman1337	9×19mm Parabellum, .380 ACP, .40 S&W, .45 ACP
	Compatible with Hi-Point C9, CF380, JCP, and JHP parts. Extremely cheap due to the high availability of the required parts kits.
Scz0rpion<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	2020, October	Receiver: CZ Scorpion Evo 3 receiver	FDM	Are We Cool Yet?	9×19mm Parabellum
	First 3D printed frame to be successfully tested with 1000+ rounds full auto in one sitting without failure.<ref>{{#invoke:citation/CS1|citation					CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>
3011 / 3011DS<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	2021, November; 2023, January (DS)	Receiver: 1911 based PDW	FDM	Deterrence Dispensed	.45 ACP, 9×19mm Parabellum, .22 TCM
	Utilizes a 1911 slide for the upper, and an AR-15 fire control group. An updated version, called the 3011DS, allows the use of double-stack higher capacity Remington and RIA magazines.
3DPD10<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	2023, April	Frame: Pistol frame	FDM	Avidity Arms	9×19mm Parabellum
	A 3D-printable frame for the Avidity Arms PD10. This design is notable as the first firearm released by commercial company designed to be 3D printed.<ref>{{#invoke:citation/CS1|citation					CitationClass=web }}</ref>

In Canadian law

Template:See also 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.