In firearms terminology and at 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 . Various firearm receivers often come with 1 or 2 sections, 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.
45-575: The Close Quarter Battle Receiver ( CQBR ) is a replacement upper receiver for the M4A1 carbine developed by the US Navy . The CQBR features a 10.3 in (262 mm) length barrel (similar to the Colt Commando short-barreled M16 variants of the past) which makes the weapon significantly more compact, thus making it easier to use in, and around, vehicles and in tight, confined spaces. The overall length of
90-423: A coffee can utilizing a cheap, simple propane torch . A small forge can even be carved out of a single soft firebrick . The primary advantage of a gas forge is the ease of use, particularly for a novice. A gas forge is simple to operate compared to coal forges, and the fire produced is clean and consistent. They are less versatile, as the fire cannot be reshaped to accommodate large or unusually shaped pieces. It
135-569: 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
180-422: A tool steel face on an anvil is to provide what some call "rebound" as well as being hard and not denting easily from misplaced hammer blows. The term rebound means it projects some of the force of the blacksmith's hammer blows back into the metal thus moving more metal at once than if there were no rebound. A good anvil can project anywhere from 50 to 99% of the energy back into the workpiece. The flat top, called
225-445: A 360-degree angle such as a hold-down tool for when the blacksmith's tongs cannot hold a workpiece as securely as it needs to be. On the front of the anvil, there is sometimes a "horn" that is used for bending, drawing out steel, and many other tasks. Between the horn and the anvil face, there is often a small area called a "step" or a "cutting table" That is used for cutting hot or cold steel with chisels, and hot cut tools without harming
270-585: A federal court in Texas ruled that the new ATF regulations exceeded the agency's statutory authority, and struck them down. 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. A Zero Percent Receiver is a rectangular billet of metal of the appropriate size to make
315-565: A finished receiver, but without any machining whatsoever. In California it is unlawful to possess an unserialized zero percent receiver, and it is unlawful to ship one into the state 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 . The receiver or frame
360-413: A firearm receiver using barrel and receiver action threads or similar methods. For the purposes of United States law , the receiver or frame is legally the firearm, 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
405-424: 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. In the case VanDerStok v. Garland , filed on June 30, 2023,
450-416: A greater distance away from the hot metals. They are very useful and found throughout the world. Tongs are used by the blacksmith for holding hot metals securely. The mouths are custom made by the smith in various shapes to suit the gripping of various shapes of metal . It is not uncommon for a blacksmith to own twenty or more pairs of tongs; traditionally, a smith would start building their collection during
495-451: A hearth is located. The forge is used by the smith to heat a piece of metal to a temperature at which it becomes easier to shape by forging , or to the point at which work hardening no longer occurs. The metal (known as the "workpiece") is transported to and from the forge using tongs , which are also used to hold the workpiece on the smithy's anvil while the smith works it with a hammer. Sometimes, such as when hardening steel or cooling
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#1732852401179540-442: A highly refined tool carefully shaped to suit a blacksmith's needs. Anvils are made of cast or wrought iron with a tool steel face welded on or of a single piece of cast or forged tool steel. Some anvils are made of only cast iron and have no tool steel face. These are not real anvils, and will not serve a blacksmith as such because they are too soft. A common term for a cast iron anvil is "ASO" or "Anvil Shaped Object". The purpose of
585-486: A soft ceramic thermal blanket (ex: Kaowool ). The burner mixes fuel and air which are ignited at the tip, which protrudes a short way into the chamber lining. The air pressure, and therefore heat, can be increased with a mechanical blower or by taking advantage of the Venturi effect . Gas forges vary in size and construction, from large forges using a big burner with a blower or several atmospheric burners to forges built out of
630-438: A velocity of 3,071 ft/s (936 m/s). This is reduced to 2,489 ft/s (759 m/s) from a barrel length of 10 inches (250 mm). Receiver (firearms) 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. A barrel may typically be affixed to
675-426: Is a ' backdraft ' where there is no fire pot, and the tuyere enters the hearth horizontally from the back wall. Coke and charcoal may be burned in the same forges that use coal, but since there is no need to convert the raw fuel at the heart of the fire (as with coal), the fire is handled differently. Individual smiths and specialized applications have fostered the development of a variety of forges of this type, from
720-445: Is also difficult to heat a small section of a piece. A common misconception is that gas forges cannot produce enough heat to enable forge- welding , but a well-designed gas forge is hot enough for any task. A finery forge is a water-powered mill where pig iron is refined into wrought iron . The anvil serves as a workbench to the blacksmith , where the metal to be forged is worked. Anvils may seem clunky and heavy, but they are
765-431: Is controlled in three ways: amount of air, the volume of fuel, and shape of the fuel/fire. Over thousands of years of forging, these devices have evolved in one form or another as the essential features of this type of forge: During operation, fuel is placed in or on the hearth and ignited. A source of moving air, such as a fan or bellows, introduces additional air into the fire through the tuyere. With additional air,
810-413: 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 . Forge A forge is a type of hearth used for heating metals , or the workplace ( smithy ) where such
855-510: Is not a firearm, purchasers do not need to pass a background check. The resulting firearm is known as a " ghost gun ". 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
900-450: Is not necessary. The short 10.3 in (262mm) barrel length requires special modifications to function reliably. The gas port is opened from 0.062 to 0.070 in (1.6 to 1.8mm). A one-piece McFarland gas ring replaces the three-piece gas ring set. The standard four-coil extractor spring is replaced with a commercial off-the-shelf (COTS) five-coil spring. An O-ring surrounds the extractor spring. The standard M4 flash hider has been replaced with
945-408: Is usually a large container full of water used by a blacksmith to quench hot metal. The slack tub is principally used to cool parts of the work during forging (to protect them, or keep the metal in one area from "spreading" for example, nearby hammer blows); to harden the steel; to tend a coal or charcoal forge; and simply to cool the work quickly for easy inspection. In bladesmithing and tool-making
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#1732852401179990-449: Is usually issued as a complete weapon system, and not just an upper receiver. The CQBR was once only available to Naval Special Warfare units (and by extension, other US Special Operations Forces units ), but the Mk 18 MOD 0 has become general issue for Visit, Board, Search, and Seizure (VBSS) missions and, as of 2006, for NCIS agents deploying to active combat zones. The Mk 18 is also used by
1035-530: The Coast Guard's Maritime Law Enforcement Specialists within both Deployable Specialized Forces and Tactical Law Enforcement Teams , as well as the United States Navy's Explosive Ordnance Disposal (EOD) Operators . It is also used by both Marine Force Recon Teams and Critical Skills operators from MARSOC , and is in most cases the standard weapons of choice for said operators where the range of an M4
1080-545: The Mk 18 MOD 0 , or the Mk 18 MOD 1 with a sightless gas block and full-length accessory rail kit. The purpose of the CQBR is to provide operators with a weapon of submachine gun size, but firing an intermediate cartridge , for scenarios such as VIP protection , urban warfare , and other close quarters battle (CQB) situations. The CQBR is designed to provide improvement over previous AR-15 / M16 -type weapons in this category. The CQBR
1125-441: The "face" is highly polished and usually has two holes (but can have more or less depending on the design). The square hole is called the hardy hole, where the square shank of the hardy tool fits. There are many different kinds of hardy tools. The smaller hole is called the pritchel hole, used as a bolster when punching holes in hot metal, or to hold tools similar to how the hardy tool does, but for tools that require being able to turn
1170-763: The Close Quarters Battle Receiver has been more or less taken on by the Naval Surface Warfare Center Crane Division (often referred to as NSWC-Crane or just "Crane") as its own project following the CQBR's removal from the SOPMOD program. Just as the Special Purpose Receiver morphed into the Special Purpose Rifle, and was type-classified as Mk 12 MOD 0/1 , the complete CQBR-equipped carbine has been type-classified as
1215-458: The M4QD flash hider for suppressor compatibility. Shortening the barrel by 50% from the original 20 inches (508 mm) pattern has a dramatic effect on the velocity of 5.56×45mm NATO ammunition. This has been demonstrated in studies using a Remington 700 bolt-action rifle, progressively shortened in barrel length and chronographed. With a barrel length of 20 inches (510 mm), the bullet travels at
1260-524: The NSN 1005-01-527-2288. The M4 carbine and M16 are not ideally suited for all missions due to their relatively long barrels, but the modularity of AR pattern rifles allows the operator to easily replace the upper receiver. One of two proposed special mission receivers that were planned for inclusion into the SOPMOD Block II kit, the CQBR has taken off on its own. Like the proposed Special Purpose Receiver ,
1305-467: The actual receiver, 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. 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
1350-403: The anvil's face. Marks on the face transfer into imperfections in the blacksmith's work. There are many types of hammer used in a blacksmith's workshop but this will name just a few common ones. Hammers can range in shape and weight from half an ounce to nearly 30 pounds depending on the type of work being done with it. Chisels are made of high carbon steel . They are hardened and tempered at
1395-407: The apprenticeship. There are various types of tongs available in the market. (1) flat tong (2) rivet or ring tong (3) straight lip fluted tong (4) gad tong Fullers are forming tools of different shapes used in making grooves or hollows. They are often used in pairs, the bottom fuller has a square shank which fits into the hardy hole in the anvil while the top fuller has a handle. The work is placed on
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1440-483: The bottom fuller and the top is placed on the work and struck with a hammer. The top fuller is also used for finishing round corners and for stretching or spreading metal. The hardy tool is a tool with a square shank that fits in a hardy hole. There are many different kinds of hardy tools such as the hot cut hardy, used for cutting hot metal on the anvil; the fuller tool, used for drawing out metal and making grooves; bending jigs - and too many others to list. A slack tub
1485-412: The coal forge described above to simpler constructions amounting to a hole in the ground with a pipe leading into it. A gas forge typically uses propane or natural gas as the fuel. One common, efficient design uses a cylindrical forge chamber and a burner tube mounted at a right angle to the body. The chamber is typically lined with refractory materials such as a hard castable refractory ceramic or
1530-402: The components to be legally classified as a firearm. "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. Because an unfinished 80% receiver
1575-417: The cutting edge while the head is left soft so it will not crack when hammered. Chisels are of two types, hot and cold chisels. The cold chisel is used for cutting cold metals while the hot chisel is for hot metals. Usually, hot chisels are thinner and therefore can not be substituted with cold chisels. Also, many smiths shape chisels as to have a simple twisted handle as to resemble a hammer, they can be used at
1620-549: The dies have many aspects to them that must be considered. They all must be properly aligned, they must be designed so the metal and the flash will flow properly and fill all the grooves, and special considerations must be made for supporting webs and ribs and the parting line location. The materials must also be selected carefully. Some factors that go into the material selection are cost, their ability to harden, their ability to withstand high pressures, hot abrasion, heat cracking, and other such things. The most common materials used for
1665-550: The drop forming process is commonly known as a power or drop hammer. These may be powered by air, hydraulics, or mechanics. Depending on how the machine is powered, the mass of the ram, and the drop height, the striking force can be anywhere from 11,000 to 425,000 pounds. The tools that are used, dies and punches, come in many different shapes and sizes, as well as materials. Examples of these shapes are flat and v-shaped which are used for open-die forging, and single or multiple-impression dies used for closed die forging. The designs for
1710-405: The fire consumes fuel faster and burns hotter (and cleaner - smoke can be thought of as escaped potential fuel). A blacksmith balances the fuel and air in the fire to suit particular kinds of work. Often this involves adjusting and maintaining the shape of the fire. In a typical coal forge, a firepot will be centred in a flat hearth. The tuyere will enter the firepot at the bottom. In operation,
1755-404: The fire's heart and to keep the coal from burning directly so that it "cooks" into coke first. If a larger fire is necessary, the smith increases the air flowing into the fire as well as feeding and deepening the coke heart. The smith can also adjust the length and width of the fire in such a forge to accommodate different shapes of work. The major variation from the forge and fire just described
1800-489: The fuel to heat metal. The designs of these forges have varied over time, but whether the fuel is coal , coke or charcoal the basic design has remained the same. A forge of this type is essentially a hearth or fireplace designed to allow a fire to be controlled such that metal introduced to the fire may be brought to a malleable state or to bring about other metallurgical effects ( hardening , annealing , and tempering as examples). The forge fire in this type of forge
1845-437: The heated material, which is very malleable, to conform to the shape of the die and die cavities. Typically only one die is needed to completely form the part. Extra space between the die faces causes some of the material to be pressed out of the sides, forming flash . This acts as a relief valve for the extreme pressure produced by the closing of the die halves and is later trimmed off of the finished part. The equipment used in
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1890-403: The hot core of the fire will be a ball of burning coke in and above the firepot. The heart of the fire will be surrounded by a layer of hot but not burning coke. Around the unburnt coke will be a transitional layer of coal being transformed into coke by the heat of the fire. Surrounding all is a ring or horseshoe-shaped layer of raw coal, usually kept damp and tightly packed to maintain the shape of
1935-403: The term will usually be changed to a "quench tank" because oil or brine is used to cool the metal. The term slack is believed to derive from the word "slake", as in slaking the heat. Drop forging is a process used to shape metal into complex shapes by dropping a heavy hammer with a die on its face onto the workpiece. The workpiece is placed into the forge. Then the impact of a hammer causes
1980-524: The upper receiver is 19.25 in (489 mm). With the stock collapsed, the overall length of the weapon is 26.75 in (679 mm). Those created as complete rifles (rather than only upper receivers) are type designated as Mk 18 MOD 0/1 . Special forces units utilize the CQBR for scenarios such as VIP protection , urban warfare , and other close quarters battle (CQB) situations. Its former preliminary National Stock Number (NSN) had been 1005-LL-L99-5996. A complete CQBR-equipped carbine now has
2025-454: The work so that it may be handled with bare hands, the workpiece is transported to the slack tub , which rapidly cools the workpiece in a large body of water . However, depending on the metal type, it may require an oil quench or a salt brine instead; many metals require more than plain water hardening. The slack tub also provides water to control the fire in the forge. A forge typically uses bituminous coal , industrial coke or charcoal as
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