{"product_id":"retroarms-cnc-koneistettu-m4-ultra-hop-up-kammio","title":"Retro Arms CNC-machined M4 ULTRA hop-up chamber","description":"\u003cp\u003eRetroArms ULTRA is designed for players who want complete control and tunability in their hop-up system. ULTRA is based on RetroArms’ proven design, but introduces major improvements: an adjustable nozzle axis, a fine-adjustable feed tube, and a redesigned inner barrel locking mechanism.\u003c\/p\u003e\n\u003cp\u003eThe chamber is CNC-machined from aircraft-grade aluminum and anodized for wear and corrosion resistance. Precise machining and a rigid structure ensure excellent accuracy and air seal, even in tuned or long-range builds.\u003c\/p\u003e\n\u003cp\u003eThe key difference of the ULTRA compared to previous versions is the adjustable nozzle axis, which allows precise fine adjustment of the hop-up chamber’s longitudinal position using the included 0.2 mm shims. This enables a perfect fit with different gearboxes, nozzles, and magazines. Note that this adjustment can affect the optimal nozzle length; in some cases, a different-length nozzle may be required.\u003c\/p\u003e\n\u003cp\u003eThe inner barrel lock has been completely redesigned: the solution uses a POM plastic C-clip and a union nut tightened over it. This combination centers the inner barrel and practically eliminates both longitudinal and rotational movement compared to a traditional C-clip-only attachment, where the inner barrel can both shift and rotate. The union nut’s outer diameter is up to 12.95 mm, so ensure compatibility with your outer barrel’s inner dimensions. Tighten the nut by hand only, do not use tools.\u003c\/p\u003e\n\u003cp\u003eThe chamber also features a modified feed tube, improving feeding reliability and compatibility with different magazines. The hop-up rubber seat is made as a flat area where the bucking is installed. The included filler rings compensate for the missing chamber material, and especially with traditional buckings the filler rings should be used. If needed, the filler rings can be adjusted for a better fit by sanding or shaping them, allowing the chamber to suit different bucking profiles.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFeatures\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eCNC-machined from aircraft-grade aluminum, anodized finish.\u003c\/li\u003e\n\u003cli\u003eAdjustable nozzle axis, adjustable in 0.2 mm increments with the included shims.\u003c\/li\u003e\n\u003cli\u003eAdjustable feed tube improves feeding reliability and compatibility.\u003c\/li\u003e\n\u003cli\u003eImproved inner barrel lock: POM C-clip + union nut, eliminating inner barrel movement and rotation.\u003c\/li\u003e\n\u003cli\u003eFlattened hop-up bucking seat and filler rings for different bucking types (e.g., ROBUST).\u003c\/li\u003e\n\u003cli\u003eR-hop compatible design.\u003c\/li\u003e\n\u003cli\u003eWeight approx. 16 g.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eWho this is for\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eRetroArms ULTRA is designed for enthusiasts and builders who want maximum accuracy and tunability. It is especially suitable for:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eDMR and precision builds where inner barrel movement must be fully eliminated.\u003c\/li\u003e\n\u003cli\u003eTuned guns where you want to perfect the compatibility between the hop-up and the nozzle.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eInstallation and tuning tips\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eBefore installation, check that the union nut’s outer diameter (max 12.95 mm) fits inside your outer barrel.\u003c\/li\u003e\n\u003cli\u003eAdjust the nozzle axis to the correct position using the included 0.2 mm shims. Start from the middle position and fine-tune based on feeding and air seal.\u003c\/li\u003e\n\u003cli\u003eTighten the union nut by hand; avoid over-tightening.\u003c\/li\u003e\n\u003cli\u003eEnsure the nozzle moves freely in the gearbox and that the contact between the nozzle and the front edge of the chamber is airtight.\u003c\/li\u003e\n\u003cli\u003eWhen using R-hop or a ROBUST bucking, adjust the feed tube and inner barrel position step by step and test-fire to confirm proper feeding and accuracy.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eTechnical specifications\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eMaterial: aircraft-grade aluminum (CNC-machined, anodized)\u003c\/li\u003e\n\u003cli\u003eWeight: approx. 16 g\u003c\/li\u003e\n\u003cli\u003eCompatibility: AR-15\/M4-type AEG rifles\u003c\/li\u003e\n\u003cli\u003eInner barrel: compatible with barrels with 8.4–8.5 mm outer diameter\u003c\/li\u003e\n\u003cli\u003eNozzle adjustment capability: via the nozzle axis, enabling optimization for different nozzle lengths\u003c\/li\u003e\n\u003cli\u003eType: ULTRA – adjustable tuning component, R-hop compatible\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Retro Arms","offers":[{"title":"Default Title","offer_id":55852531155292,"sku":"9430","price":893.86,"currency_code":"NOK","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0612\/6636\/2610\/files\/4699_hop-komora-ar15-ultra_4555.png?v=1761845238","url":"https:\/\/atom-airsoft.fi\/en-no\/products\/retroarms-cnc-koneistettu-m4-ultra-hop-up-kammio","provider":"Atom Airsoft","version":"1.0","type":"link"}