Pancor Jackhammer The Pancor Jackhammer is an American fully - automatic shotgun designed by the guns maker John Andersen and the Pancor Corporation in 1984 . It didn ' t sold any example , but it ' sfuturist looking appearance made it popular in many video - games . Description . The Jackhammer automatic shotgun was developed by the US firearms designer John Andersen , who requested patents for the basic design of this shotgun in 1984 . Since that time and until the late 1990s he continued to develop and improve his basic design but as far as I know failed to attract any serious buyers . In fact , only few working prototypes of the Jackhammer were ever built . Some sources stated that only two fully automatic prototypes are exist , and the Jane ' s Defense Library 2000 stated that the development is complete but production never began . At my opinion , the Jackhammer is a solution that still to have a question , and it possess some questionable features that can distract any serious military or police buyer . But , anyway , it is interesting design and well deserves its place both here and in the general firearms history . The Jackhammer is a gas operated , fully automatic only shotgun . The gas system of the Jackhammer consists of the gas cylinder , formed around the movable barrel . The gas piston is formed by the collar , fixed to the barrel just ahead of the gas port that feeds the gases from the barrel into the gas cylinder . When gun is fired , the powder gases are fed into the gas cylinder and began to push the gas piston and the whole barrel to the front , against the pressure of the return spring . The return spring is located around the barrel , ahead of the gas piston . When barrel moves forward , it first disconnects itself from the chamber with fired cartridge , and then , continuing to move forward , operates the action rod that connects the barrel and the feed and firing system . The action rod reciprocates with the barrel and has two downward projections on its rear end . These projections act on the cam slots , cut on the outer surface of the cylinder that contains the ammunition . When barrel and action rod go forward , the forward projection on the action rod rotates the cylinder 12 clockwise . On the backward strike of the barrel and action rod the rear projections rotates the cylinder another 12 to align next chamber with the barrel . At the final stage of the cycle rear part of the barrel reconnects itself with fresh chamber to achieve a gas - tight connection . At the same time the rear part of the action rod engages the striker , located behind the upper chamber of the cylinder , and cocks it . If the trigger is still pulled all the way back when the reloading cycle is completed , the sear will be released automatically and gun will fire again . There is no provisions for the dedicated semi - automatic single - shot mode - due to the relatively low rate of fire the single shots can be obtained by the quick pulls on the trigger . The feed system consists of the 10 shot , revolver type detachable cylinders , named " Ammo Cassette " . The cassette may have 10 chambers for more or less conventional 12 gauge shotgun shells , or may be designed like the " cap and ball " era revolver cylinders . In the latter case , each chamber is factory pre - loaded with powder , primer and a projectiles of one or another type , then hermetically sealed in the plastic film cover . Prior to load the " Ammo Cassette " into the gun , one must remove the plastic sealing and then insert the cassette . When all charges from the cassette are fired , it can be disposed of or sent to the factory for reload . The manual cocking for the first shot and the magazine replace process are controlled by the sliding forward handguard . When the handguard is pulled forward , it engages the barrel and pulls it forward and then back , to cycle the action . To remove the Ammo Cassette , one must pull the trigger half the way back ( presumably with the safety engaged ) , and then pull the handguard forward . This will withdraw the barrel from contact with the chamber of cassette and then remove the cassette axis forward , so the ammo cassette will be free to fall out of the gun . In the forwardmost position the slide will be automatically held by the release latch , located at the front of the handguard , thus leaving the shooters ' non - firing hand free to insert the fresh " cassette " into its place . As soon as the ammo cassette is in its place , the shooter must push the slide release , so the barrel and the slide will go back under the pressure of the return spring , locking the cassette in place and cocking the gun . The striker can be manually cocked or de - cocked using the cocking handle , located inside the butt . The barrel of the Jackhammer can be easily replaced by removing the muzzle cover and return spring , then rotating barrel 90 either side do disconnect if from the action rod and , finally , pulling the barrel out of the gun . The new barrel then could be dropped in and rotated 90 to engage with the action rod . Then goes the return spring and the muzzle cover . The conventional open sights are mounted within the integral carrying handle . Use of the Magazine as a Anti - Personnell Mine . As an interesting additional feature , it is possible to take the drum magazine off the firearm , attach a detonator , and use it as an anti - personnel mine that fires all of the cartridges at once when tripped . The manufacturer advertised this as the " Beartrap .