VFC MP7 HPA Drop-In Kit (BYO PolarStar Engine Edition)
Due to overwhelming demand, Bull Craft is offering a new option: you send in your PolarStar F2 or Jack engine, and we build your custom drop‑in gearbox around it. This kit includes all the internal components of our standard drop‑in build — minus the engine — and ships back fully assembled, tuned, and ready to run.
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?️ What’s Included
• Custom gearbox designed, printed, processed, and assembled in‑house
• Choice of flat/straight or curved trigger
• 6.03mm upgraded inner barrel
• CNC aluminum anodized threaded outer barrel (14mm CCW or 12mm CW original spec)
• Upgraded bucking for proven consistency
• OEM hop‑up unit (custom design in development)
• Printed barrel safety cap for shipping
• Spec sheet tuned for low‑altitude, humid environments
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? What You Provide
• Your PolarStar F2 or Jack engine — shipped to us for integration
• If your engine does not include a macro line, you’ll need to purchase an Amped IGL
• Optional upgrades like Amped IGL or GSI Aluminum Hop‑Up Arm (available separately)
⚠️ Important: You must ship your PolarStar engine to us for the gearbox build.
• You do not need to send in your MP7 unless you want us to complete the full install ($75).
• If your engine requires service (cleaning, rebuilding, or replacement parts such as o‑rings), additional charges will apply. We’ll contact you before proceeding.
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? Performance & Install Highlights
• Zero alignment issues — gearbox locks engine in place
• Minimal body modification required
• Easy hop‑up and bucking maintenance without voiding warranty
• Trigger install requires patience, but video guides are available
• Superb air efficiency and flawless design trusted worldwide
? Due to the scarcity of VFC MP7 AEGs (only available used), we will continue offering this option to meet demand.
