{"product_id":"polarstar-jack-direct-attachment-conversion-set","title":"Polarstar JACK Direct Attachment Conversion Set","description":"\u003ch2\u003ePolarStar JACK Direct Attachment Conversion Set\u003c\/h2\u003e\n\n\u003cp\u003e\u003cstrong\u003eThe PolarStar JACK Direct Attachment Conversion Set replaces the original front cylinder of a PolarStar JACK HPA engine and connects the engine directly to the Polarstar \"Hop Up Thing\" Chamber for AEG\/HPA M4 V2. This creates a single rigid assembly consisting of the HPA engine, hop-up chamber and inner barrel.\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cp\u003eIn a conventional HPA installation, the gearbox shell positions the engine in relation to the hop-up chamber. Dimensional differences, movement between components or an incorrectly aligned gearbox shell can allow the nozzle to tilt or move sideways. Even a small alignment error can affect BB feeding, air seal, hop-up consistency and grouping.\u003c\/p\u003e\n\n\u003cp\u003eThe Direct Attachment system transfers the alignment function from the gearbox shell directly to the connection between the JACK engine and the hop-up chamber. The upper section of the gearbox shell is therefore no longer responsible for keeping the engine and hop-up correctly aligned.\u003c\/p\u003e\n\n\u003ch3\u003eRigid monolithic assembly\u003c\/h3\u003e\n\n\u003cp\u003eThe conversion set consists of two main components:\u003c\/p\u003e\n\n\u003cul\u003e\n\u003cli\u003ePolarStar JACK Direct Attach Front Cylinder\u003c\/li\u003e\n\u003cli\u003eInternal threaded adapter\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eThe original front cylinder is removed from the JACK engine and replaced with the Direct Attachment components. The compatible PolarStar hop-up chamber is then threaded directly onto the adapter.\u003c\/p\u003e\n\n\u003cp\u003eOnce assembled, the JACK engine, hop-up chamber and inner barrel form one rigid unit. Because the main components cannot move independently, the nozzle remains mechanically aligned with the inner-barrel bore.\u003c\/p\u003e\n\n\u003ch3\u003eMinimal nozzle deflection\u003c\/h3\u003e\n\n\u003cp\u003eAccording to PolarStar, the Direct Attachment system supports the nozzle with approximately 0.0025 inches, or about 0.064 mm, of clearance on each side. This tight support effectively prevents the nozzle from leaning or moving sideways while loading a BB.\u003c\/p\u003e\n\n\u003cp\u003eReducing nozzle movement can help prevent feeding and consistency problems commonly known as mid-cap syndrome. This can occur when pressure from a fully loaded mid-cap magazine affects the position of the hop-up chamber or nozzle.\u003c\/p\u003e\n\n\u003ch3\u003eConsistent BB loading and hop-up performance\u003c\/h3\u003e\n\n\u003cp\u003eWhen the nozzle loads each BB into the hop-up chamber in the same position and at the same depth, the contact between the BB, hop-up bucking and nub remains more repeatable.\u003c\/p\u003e\n\n\u003cp\u003eConsistent BB positioning and nozzle engagement can support a more stable air seal, repeatable hop-up effect and tighter groupings. The system also removes the need to align the JACK engine by shimming it against the upper section of the gearbox shell.\u003c\/p\u003e\n\n\u003ch3\u003eDesigned for advanced HPA builds\u003c\/h3\u003e\n\n\u003cp\u003eThe JACK Direct Attachment Conversion Set is not a drop-in component for an unmodified gearbox. Because the engine connects directly to the hop-up chamber, the upper section of a conventional gearbox shell is no longer required and may need to be removed.\u003c\/p\u003e\n\n\u003cp\u003eThe electronics, trigger, selector and other lower gearbox components still require a suitable supporting structure. Depending on the build, this can be:\u003c\/p\u003e\n\n\u003cul\u003e\n\u003cli\u003eA modified V2 gearbox shell\u003c\/li\u003e\n\u003cli\u003eA compatible replacement gearbox lower\u003c\/li\u003e\n\u003cli\u003eA suitable 3D-printed lower structure\u003c\/li\u003e\n\u003cli\u003eA completely custom chassis or replica body\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eThe system can be used to correct alignment problems in an M4-style JACK build or as the foundation for a custom or 3D-printed HPA replica.\u003c\/p\u003e\n\n\u003ch3\u003eCompatibility\u003c\/h3\u003e\n\n\u003cul\u003e\n\u003cli\u003eDesigned specifically for the PolarStar JACK HPA engine\u003c\/li\u003e\n\u003cli\u003eReplaces the original JACK front cylinder\u003c\/li\u003e\n\u003cli\u003eCompatible only with the Polarstar \"Hop Up Thing\" Chamber for AEG\/HPA M4 V2\u003c\/li\u003e\n\u003cli\u003eNot compatible with conventional AEG or other aftermarket hop-up chambers\u003c\/li\u003e\n\u003cli\u003eIntended for modified V2 gearbox installations and custom builds\u003c\/li\u003e\n\u003cli\u003eNot a drop-in component for an unmodified gearbox shell\u003c\/li\u003e\n\u003cli\u003eThis JACK version is not compatible with PolarStar F2 or Kythera engines\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eRequired additional components\u003c\/h3\u003e\n\n\u003cul\u003e\n\u003cli\u003ePolarStar JACK HPA engine\u003c\/li\u003e\n\u003cli\u003ePolarstar \"Hop Up Thing\" Chamber for AEG\/HPA M4 V2\u003c\/li\u003e\n\u003cli\u003eCompatible inner barrel\u003c\/li\u003e\n\u003cli\u003eCompatible hop-up bucking and nub\u003c\/li\u003e\n\u003cli\u003eModified gearbox shell, compatible gearbox lower or custom supporting structure\u003c\/li\u003e\n\u003cli\u003eCompatible electronics, trigger and selector components\u003c\/li\u003e\n\u003cli\u003eOther air-system components required for operating the JACK engine\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eInstallation notes\u003c\/h3\u003e\n\n\u003cul\u003e\n\u003cli\u003eThe original front cylinder must be removed from the JACK engine.\u003c\/li\u003e\n\u003cli\u003eThe original threaded gearbox interface must be removed from the compatible PolarStar hop-up chamber.\u003c\/li\u003e\n\u003cli\u003eApply suitable grease to the internal sealing surface of the JACK adapter according to PolarStar’s instructions.\u003c\/li\u003e\n\u003cli\u003eThe hop-up chamber is threaded directly onto the Direct Attachment adapter.\u003c\/li\u003e\n\u003cli\u003eStart the threads carefully to prevent cross-threading.\u003c\/li\u003e\n\u003cli\u003eDo not force the components together if the threads do not engage smoothly.\u003c\/li\u003e\n\u003cli\u003eThe hop-up feed tube must be correctly aligned for smooth magazine insertion.\u003c\/li\u003e\n\u003cli\u003eThe installation requires technical experience and modification of the gearbox or supporting chassis.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eInstallation guide\u003c\/h3\u003e\n\n\u003cp\u003eRead the official PolarStar Direct Attachment guide before beginning the installation:\u003c\/p\u003e\n\n\u003cp\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0023\/7466\/4301\/files\/PolarStar_Airsoft_Direct_Attachment_Guide_May_V1.1.pdf\" target=\"_blank\" rel=\"noopener noreferrer\"\u003e\u003cstrong\u003ePolarStar Direct Attachment Installation Guide (PDF)\u003c\/strong\u003e\u003c\/a\u003e\u003c\/p\u003e\n\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\n\u003cul\u003e\n\u003cli\u003eConnects the PolarStar JACK directly to the compatible hop-up chamber\u003c\/li\u003e\n\u003cli\u003eCreates a rigid engine, hop-up and inner-barrel assembly\u003c\/li\u003e\n\u003cli\u003eMaintains precise nozzle-to-barrel alignment\u003c\/li\u003e\n\u003cli\u003eEffectively eliminates independent nozzle deflection\u003c\/li\u003e\n\u003cli\u003eApproximately 0.0025\" \/ 0.064 mm nozzle clearance per side\u003c\/li\u003e\n\u003cli\u003eHelps reduce mid-cap syndrome\u003c\/li\u003e\n\u003cli\u003eSupports consistent BB loading and nozzle engagement depth\u003c\/li\u003e\n\u003cli\u003eCan improve air-seal and hop-up consistency\u003c\/li\u003e\n\u003cli\u003eRemoves the need for gearbox-shell alignment shimming\u003c\/li\u003e\n\u003cli\u003eSuitable for modified V2 and custom HPA builds\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003ePackage contents\u003c\/h3\u003e\n\n\u003cul\u003e\n\u003cli\u003ePolarStar JACK Direct Attach Front Cylinder\u003c\/li\u003e\n\u003cli\u003eInternal threaded adapter\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eNot included\u003c\/h3\u003e\n\n\u003cul\u003e\n\u003cli\u003ePolarStar JACK HPA engine\u003c\/li\u003e\n\u003cli\u003ePolarstar \"Hop Up Thing\" Chamber for AEG\/HPA M4 V2\u003c\/li\u003e\n\u003cli\u003eInner barrel\u003c\/li\u003e\n\u003cli\u003eHop-up bucking and nub\u003c\/li\u003e\n\u003cli\u003eGearbox shell or replacement gearbox lower\u003c\/li\u003e\n\u003cli\u003eElectronics, trigger or selector components\u003c\/li\u003e\n\u003cli\u003eAir hose, regulator or HPA tank\u003c\/li\u003e\n\u003cli\u003eReplica or other components shown in product images\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical specifications\u003c\/h3\u003e\n\n\u003cul\u003e\n\u003cli\u003eManufacturer: PolarStar\u003c\/li\u003e\n\u003cli\u003eProduct: JACK Direct Attachment Conversion Set\u003c\/li\u003e\n\u003cli\u003eProduct type: direct-attachment conversion set for an HPA engine\u003c\/li\u003e\n\u003cli\u003eCompatible engine: PolarStar JACK\u003c\/li\u003e\n\u003cli\u003eCompatible hop-up chamber: Polarstar \"Hop Up Thing\" Chamber for AEG\/HPA M4 V2 only\u003c\/li\u003e\n\u003cli\u003eReplaces: original PolarStar JACK front cylinder\u003c\/li\u003e\n\u003cli\u003eConstruction: two-piece front-cylinder and adapter system\u003c\/li\u003e\n\u003cli\u003eApproximate nozzle clearance: 0.0025\" \/ 0.064 mm per side\u003c\/li\u003e\n\u003cli\u003eInstallation type: modified or custom installation\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"PolarStar Engineering \u0026 Machine, LLC","offers":[{"title":"Default Title","offer_id":58558998610268,"sku":"10001490","price":31.46,"currency_code":"EUR","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0612\/6636\/2610\/files\/Photoroom_20260616_110611.webp?v=1786020533","url":"https:\/\/atom-airsoft.fi\/en-fr\/products\/polarstar-jack-direct-attachment-conversion-set","provider":"Atom Airsoft","version":"1.0","type":"link"}