{"product_id":"polarstar-fusion-engine-drop-in-kit-m249","title":"PolarStar Fusion Engine Drop-In Kit — M249","description":"\u003cdiv style=\"background:#edfaf1;border-left:4px solid #27ae60;padding:12px 16px;border-radius:0 6px 6px 0;margin:0 0 16px;font-size:13px;\"\u003e\n\u003cstrong style=\"color:#1a6b3a;\"\u003ePolarStar Fusion Engine Drop-In Kit, M249.\u003c\/strong\u003e The Fusion built for the M249 support platform. A dual solenoid closed-bolt engine on a machined aluminium chassis, supplied with the FCU, switchboard, wire harness and the parts specific to the M249 conversion.\n\u003c\/div\u003e\u003cp\u003eA support weapon is the build that benefits most from going to air. A box magazine will feed a far higher rate than a gearbox wants to sustain, and the thing that usually gives out first on an electric M249 is the gearbox itself — stripped pistons, cracked shells, the rest of it. Replacing the whole gearbox with a machined aluminium chassis and a solenoid takes that failure mode off the table, which is why so many long-serving LMGs in this country run the Fusion.\u003c\/p\u003e\u003cp\u003eThis is a complete chassis swap, not a drop-in cylinder. The entire original gearbox comes out and the Fusion assembly goes in, carrying its own trigger micro-switch fitted to the frame. PolarStar include the filter fitting already installed, the FCU, the switchboard, the wire harness and whatever extra pieces the M249 specifically needs — so the box contains the conversion rather than the start of one.\u003c\/p\u003e\u003cp\u003eIt is a dual solenoid design running a closed bolt, and the practical consequence is that you set firing air and feeding separately. The poppet governs the air behind the BB and the nozzle governs how it is loaded, and because they are independent you can chase rate of fire without wrecking your velocity, or settle the feed on a box mag that is being asked to work hard. Closed bolt also makes the engine less fussy about hop-up setup than an open-bolt system, which matters on a gun firing long bursts.\u003c\/p\u003e\u003cp\u003ePolarStar quote 550 fps on a 0.20 g BB at 120 psi and 30 rounds per second and above. Neither of those is a UK number — the point is headroom. Six nozzles of differing restriction shift the whole adjustment window up or down, so you tune down to your site limit from a position of surplus rather than trying to squeeze more out of something marginal. Set for field energy and running restrictive internals, the same engine returns over 400 shots from a 13\/3000 bottle.\u003c\/p\u003e\u003ch2 style=\"font-size:16px;color:#1B3A6B;margin:18px 0 8px;\"\u003eSpecifications\u003c\/h2\u003e\u003ctable style=\"width:100%;border-collapse:collapse;font-size:13px;margin:0 0 18px;\"\u003e\n\u003ctr style=\"background:#1B3A6B;color:#fff;\"\u003e\n\u003cth style=\"padding:7px 12px;text-align:left;\"\u003eSpecification\u003c\/th\u003e\n\u003cth style=\"padding:7px 12px;text-align:left;\"\u003eDetail\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background:#f5f5f5;\"\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eType\u003c\/td\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eComplete drop-in HPA engine, replaces the AEG gearbox\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003ePlatform\u003c\/td\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eM249\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background:#f5f5f5;\"\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eFitment\u003c\/td\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eClassic Army and A\u0026amp;K M249 pattern\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eChassis\u003c\/td\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eFull CNC-machined lightweight aluminium\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background:#f5f5f5;\"\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eOperation\u003c\/td\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eDual solenoid, closed bolt\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eAdjustment\u003c\/td\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003ePoppet and nozzle adjustable independently\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background:#f5f5f5;\"\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eVelocity\u003c\/td\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003e550 fps with 0.20 g at 120 psi\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eRate of fire\u003c\/td\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003e30 rps and above in most configurations\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background:#f5f5f5;\"\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eAir efficiency\u003c\/td\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003e400 plus shots from a 13\/3000 at 1.5 J with 0.28 g\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eEfficiency test setup\u003c\/td\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eBlack poppet, blue nozzle, 6.05 x 375 mm barrel\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background:#f5f5f5;\"\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eNozzle options\u003c\/td\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eSix, each with a different restriction level\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eIncluded\u003c\/td\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eFilter fitting fitted, FCU, switchboard, wire harness and the model-specific parts for the conversion\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background:#f5f5f5;\"\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eNot included\u003c\/td\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eHPA tank, regulator and line, battery\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eGel ball\u003c\/td\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eCan be configured for gel ball use on request\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background:#f5f5f5;\"\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eFirst released\u003c\/td\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003e2011\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003eBrand\u003c\/td\u003e\n\u003ctd style=\"padding:7px 12px;border:1px solid #eee;\"\u003ePolarStar\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003ch2 style=\"font-size:16px;color:#1B3A6B;margin:18px 0 8px;\"\u003eGood to know\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eWhat does the box actually contain?\u003c\/strong\u003e The engine and chassis with the filter fitting fitted, the FCU, the switchboard, the wire harness and the M249-specific conversion parts. You add a bottle, a regulator and line, and a battery.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill 550 fps get me thrown off site?\u003c\/strong\u003e That is the figure at 120 psi, not a setting you would play on. You tune to your venue's limit at the regulator and confirm it over a chronograph — support weapons usually sit under a tighter limit and a minimum engagement distance, so check both.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich M249 does it fit?\u003c\/strong\u003e The Classic Army and A\u0026amp;K pattern. If yours is another make, \u003ca href=\"\/pages\/contact-us\" style=\"color:#1B3A6B;\"\u003esend us the model\u003c\/a\u003e before ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use it for gel ball?\u003c\/strong\u003e PolarStar can configure a Fusion for gel ball, but it is a build-to-order change rather than a switch on the unit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the trigger any good?\u003c\/strong\u003e The micro-switch is fitted to the frame rather than adapted to it, so you get a defined break, a hard stop and a short reset.\u003c\/p\u003e\u003cdiv style=\"background:#fffbe6;border-left:4px solid #f0d060;padding:12px 16px;border-radius:0 6px 6px 0;margin:0 0 16px;font-size:13px;\"\u003e\n⚠ \u003cstrong\u003eBefore you order:\u003c\/strong\u003e work out where the bottle is going to live on an M249 and how the line will route to it. The engine is the easy part of this conversion — the air rig and the room for it are what catch people out on a support build.\n\u003c\/div\u003e\u003cdiv style=\"background:#1B3A6B;color:#fff;padding:12px 16px;border-radius:6px;margin:18px 0 0;font-size:13px;\"\u003e\n\u003cstrong style=\"color:#fff;\"\u003e💡 Titan Forge Airsoft tip:\u003c\/strong\u003e You will need a bottle and an air rig to run it: start with our \u003ca href=\"\/collections\/hpa-tanks\" style=\"color:#cdd6f4;\"\u003eHPA tanks\u003c\/a\u003e and \u003ca href=\"\/collections\/hpa-regulators\" style=\"color:#cdd6f4;\"\u003eregulators\u003c\/a\u003e. We are an HPA tech centre and will fit, tune and chronograph the whole thing if you would rather not — see the \u003ca href=\"\/pages\/hpa-tech-service\" style=\"color:#cdd6f4;\"\u003etech service\u003c\/a\u003e.\n\u003c\/div\u003e","brand":"Polarstar","offers":[{"title":"Default Title","offer_id":55696832725368,"sku":"54537520","price":519.95,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0562\/8097\/3450\/files\/PolarStarFusionDrop-InKitM249_TitanForgeAirsoft_1.webp?v=1791727226","url":"https:\/\/www.titanforgeairsoft.com\/products\/polarstar-fusion-engine-drop-in-kit-m249","provider":"Titan Forge Airsoft","version":"1.0","type":"link"}