Direct impingement is a type of gas operation for a firearm that directs gas from a fired cartridge indirectly (through the barrel, through a gas block, and then through a gas tube) into the bolt carrier or slide assembly to cycle the action. Firearms using direct impingement are theoretically lighter, more accurate, and less expensive than firearms using cleaner and cooler gas piston systems.
Firearms featuring a direct impingement design are, in principle, capable of being constructed so as to be slightly lighter than their piston operated counterparts (due to the lack of any additional hardware other than the gas tube, which is required to channel the gas from the barrel back towards the action). Unlike conventional gas-operated firearms, direct impingement does away with a separate gas cylinder, piston, and operating rod assembly. High-pressure gas acts directly upon the bolt and carrier, thereby saving weight, lowering manufacturing costs, and reducing the mass of the operating parts, and thereby the wear on mechanical parts due to movement. By removing the gas piston, the potential amount of moving mass is lowered, thus decreasing the potential for firearm movement and barrel distortion before the bullet leaves the barrel.[1]
In the AR-10 and AR-15 designs, the gas directed out of the bolt carrier group may improve reliability in some conditions. The jet of gas can blow debris away from the ejection port, preventing ingress of material which, in other designs, would infiltrate the mechanism and foul the gun.
Disadvantages
The main disadvantage of direct impingement is that the breech of the firearm's firing mechanism becomes fouled more quickly than long or short stroke piston firearms by direct exposure of the impinging region of the bolt carrier to the residues of the burned cartridge propellant each time the firearm cycles. This is caused by particles suspended in high-temperature gas condensing on the bolt face and primary operating mechanism. The combustion gases contain vaporized metals, carbon, and impurities in a gaseous state until they contact the relatively cooler operating parts. These deposits increase friction on the bolt's camming system, leading to malfunctions, so that frequent and thorough cleaning is required to ensure reliability. The amount of fouling depends upon the rifle's design as well as the type of propellant powder used.[2]
A further disadvantage of direct impingement is that combustion gases heat the bolt and bolt carrier as the firearm operates. This heating causes essential lubricant to be "burned off". Lack of proper lubrication is the most common cause of weapon malfunctions. These combined factors reduce service life of these parts, reliability, and mean time between failures.[3]
Variables
The operation of the system is highly dependent on the length of both barrel and gas tube which transports gas from the barrel to the bolt. Using too short a gas tube can result in increased pressure inside the bolt assembly and increased rate of automatic fire, both of which can have detrimental effect on the weapon and accuracy of shots. The use of a suppressor also increases gas pressure, further aggravating the situation. The problem can be reduced by using a longer gas tube, moving the gas port on the barrel further forward, and/or by installing an adjustable gas block to provide the right amount of gas pressure depending on the desired operating mode.[1]
History
The first experimental rifle using a direct impingement system was the French Rossignol ENT B1 automatic rifle followed by Rossignol's B2, B4 and B5. The first successful production weapon was the MAS 40 rifle adopted in March 1940. The Swedish Automatgevär m/42 is another well-known example. Both the French and Swedish rifles use a simple system whereby the gas tube acts as a piston with a cylinder recess in the bolt carrier.
Stoner bolt and carrier piston system
Stoner internal piston action system
A widely known direct impingement gas system is the one used in the AR-15 style rifle, first patented by ArmaLite for use in the AR-10. The original AR-10 action (later developed into the ArmaLite AR-15, M16 rifle and M4 carbine) designed by Eugene Stoner is commonly called a direct impingement system, but it does not utilize a conventional direct impingement system. In U.S. Patent 2,951,424, the designer states: ″This invention is a true expanding gas system instead of the conventional impinging gas system.″[4] Gas is routed from a port in the barrel through a gas tube, directly to a chamber inside the bolt carrier. The bolt within the bolt carrier is fitted with piston rings to contain the gas. In effect, the bolt and carrier act as a gas piston and cylinder. The subtleties involved in ArmaLite's patent on the gas system[5] significantly diverge from classical direct impingement; upon firing, the pressurized propellant gasses exit the barrel via the gas port and travel the length of the gas tube, but instead of simply applying the inertia necessary to cycle the weapon directly to the bolt carrier, the gas is funneled inside the bolt carrier wherein the increase in pressure results in the bolt itself acting as a piston, forcing the bolt carrier away from the barrel face.[6]
^"ARMALITE TECHNICAL NOTE 54: DIRECT IMPINGEMENT VERSUS PISTON DRIVE" (PDF). Armalite. 3 July 2010. Archived from the original (PDF) on 5 September 2012.
Sources
Centre des archives de l'armement, Châtellerault. National Armament Archives Center.
United States Patent Office, Patent No. 2951424 - Gas Operated Bolt and Carrier System, Sep 6 1960.
External links
How Does It Work: Direct Gas Impingement Forgotten Weapons
March 10, 2023
direct, impingement, type, operation, firearm, that, directs, from, fired, cartridge, indirectly, through, barrel, through, block, then, through, tube, into, bolt, carrier, slide, assembly, cycle, action, firearms, using, direct, impingement, theoretically, li. Direct impingement is a type of gas operation for a firearm that directs gas from a fired cartridge indirectly through the barrel through a gas block and then through a gas tube into the bolt carrier or slide assembly to cycle the action Firearms using direct impingement are theoretically lighter more accurate and less expensive than firearms using cleaner and cooler gas piston systems direct impingement Contents 1 Advantages 2 Disadvantages 3 Variables 4 History 4 1 Stoner bolt and carrier piston system 5 See also 6 References 7 Sources 8 External linksAdvantages EditFirearms featuring a direct impingement design are in principle capable of being constructed so as to be slightly lighter than their piston operated counterparts due to the lack of any additional hardware other than the gas tube which is required to channel the gas from the barrel back towards the action Unlike conventional gas operated firearms direct impingement does away with a separate gas cylinder piston and operating rod assembly High pressure gas acts directly upon the bolt and carrier thereby saving weight lowering manufacturing costs and reducing the mass of the operating parts and thereby the wear on mechanical parts due to movement By removing the gas piston the potential amount of moving mass is lowered thus decreasing the potential for firearm movement and barrel distortion before the bullet leaves the barrel 1 In the AR 10 and AR 15 designs the gas directed out of the bolt carrier group may improve reliability in some conditions The jet of gas can blow debris away from the ejection port preventing ingress of material which in other designs would infiltrate the mechanism and foul the gun Disadvantages EditThe main disadvantage of direct impingement is that the breech of the firearm s firing mechanism becomes fouled more quickly than long or short stroke piston firearms by direct exposure of the impinging region of the bolt carrier to the residues of the burned cartridge propellant each time the firearm cycles This is caused by particles suspended in high temperature gas condensing on the bolt face and primary operating mechanism The combustion gases contain vaporized metals carbon and impurities in a gaseous state until they contact the relatively cooler operating parts These deposits increase friction on the bolt s camming system leading to malfunctions so that frequent and thorough cleaning is required to ensure reliability The amount of fouling depends upon the rifle s design as well as the type of propellant powder used 2 A further disadvantage of direct impingement is that combustion gases heat the bolt and bolt carrier as the firearm operates This heating causes essential lubricant to be burned off Lack of proper lubrication is the most common cause of weapon malfunctions These combined factors reduce service life of these parts reliability and mean time between failures 3 Variables EditThe operation of the system is highly dependent on the length of both barrel and gas tube which transports gas from the barrel to the bolt Using too short a gas tube can result in increased pressure inside the bolt assembly and increased rate of automatic fire both of which can have detrimental effect on the weapon and accuracy of shots The use of a suppressor also increases gas pressure further aggravating the situation The problem can be reduced by using a longer gas tube moving the gas port on the barrel further forward and or by installing an adjustable gas block to provide the right amount of gas pressure depending on the desired operating mode 1 History EditThe first experimental rifle using a direct impingement system was the French Rossignol ENT B1 automatic rifle followed by Rossignol s B2 B4 and B5 The first successful production weapon was the MAS 40 rifle adopted in March 1940 The Swedish Automatgevar m 42 is another well known example Both the French and Swedish rifles use a simple system whereby the gas tube acts as a piston with a cylinder recess in the bolt carrier Stoner bolt and carrier piston system Edit Stoner internal piston action system A widely known direct impingement gas system is the one used in the AR 15 style rifle first patented by ArmaLite for use in the AR 10 The original AR 10 action later developed into the ArmaLite AR 15 M16 rifle and M4 carbine designed by Eugene Stoner is commonly called a direct impingement system but it does not utilize a conventional direct impingement system In U S Patent 2 951 424 the designer states This invention is a true expanding gas system instead of the conventional impinging gas system 4 Gas is routed from a port in the barrel through a gas tube directly to a chamber inside the bolt carrier The bolt within the bolt carrier is fitted with piston rings to contain the gas In effect the bolt and carrier act as a gas piston and cylinder The subtleties involved in ArmaLite s patent on the gas system 5 significantly diverge from classical direct impingement upon firing the pressurized propellant gasses exit the barrel via the gas port and travel the length of the gas tube but instead of simply applying the inertia necessary to cycle the weapon directly to the bolt carrier the gas is funneled inside the bolt carrier wherein the increase in pressure results in the bolt itself acting as a piston forcing the bolt carrier away from the barrel face 6 See also EditGlossary of firearms terminology Gas delayed blowback Repeating rifleReferences Edit a b Sweeney Patrick AR 15 Direct Impingement Vs Gas Piston Gun Digest Retrieved 9 August 2021 Maddox Brandon Direct Impingement vs Gas Piston Settling the Debate Silencer Central Retrieved 9 August 2021 Major Thomas P Ehrhart Increasing Small Arms Lethality in Afghanistan Taking Back the Infantry Half Kilometer US Army 2009 Patent US2951424 GAS OPERATED BOLT AND CARRIER SYSTEM Retrieved 2013 04 11 Eugene Stoner 1956 Gas operated bolt and carrier system US2951424A https patents google com patent US2951424A en ARMALITE TECHNICAL NOTE 54 DIRECT IMPINGEMENT VERSUS PISTON DRIVE PDF Armalite 3 July 2010 Archived from the original PDF on 5 September 2012 Sources EditCentre des archives de l armement Chatellerault National Armament Archives Center Huon Jean Proud Promise French Semiautomatic Rifles 1898 1979 Collector Grade Publications 1995 ISBN 0 88935 186 4 United States Patent Office Patent No 2951424 Gas Operated Bolt and Carrier System Sep 6 1960 External links EditHow Does It Work Direct Gas Impingement Forgotten Weapons Retrieved from https en wikipedia org w index php title Direct impingement amp oldid 1129006654, wikipedia, wiki, book, books, library,
