VFC MP7 HPA Drop-In Gearbox — Customer-Supplied PolarStar Edition

Bring the engine. We do the hard part.

Due to overwhelming demand and the scarcity of VFC MP7 AEGs, Bull Craft now offers a Customer-Supplied Engine (BYO) Drop-In HPA Gearbox. You send us your PolarStar F2 or JACK, and we build a fully assembled, tuned, and ready-to-run MP7 HPA gearbox around it.

This is the same proven Bull Craft drop-in system—minus the engine—professionally integrated, aligned, and tested in-house. No guesswork. No DIY frustration. Just a locked-in HPA solution that works.

🛠️ What’s Included

• Custom MP7 gearbox designed, printed, processed, and assembled in-house
• Precision engine integration — engine locked solid with zero alignment issues
• Choice of flat/straight or curved trigger
• 6.03mm upgraded inner barrel
• CNC-machined anodized aluminum outer barrel
  – 14mm CCW or 12mm CW original-spec threading
• Upgraded bucking for proven consistency
• OEM hop-up unit
• Printed barrel safety cap for shipping
• Spec sheet tuned for low-altitude, humid environments

Shipped fully assembled and tuned—ready to drop in and play.

📦 What You Provide

• Your PolarStar F2 or JACK engine, shipped to Bull Craft for integration
• If your engine does not include a macro line, an Amped IGL is required
• Optional upgrades are available separately, including the Amped IGL and GSI Aluminum Hop-Up Arm

⚠️ Important Notes

• You must ship your engine to us for this build.

• You do not need to send your MP7 unless you want full installation service for $75.

• If your engine requires servicing, cleaning, O-rings, or rebuild parts, we will contact you before proceeding with any additional cost.

🔩 Performance & Installation Highlights

• Engine is positively locked—no shifting or misalignment
• Minimal body modification required
• Hop-up and bucking are serviceable without voiding the warranty
• Excellent air efficiency and reliability
• Trusted worldwide by MP7 HPA users

Trigger installation requires care. Visit our VFC MP7 HPA Support & Troubleshooting page for the complete gearbox installation guide, selector-switch adjustment, double-firing solution, and hop-up maintenance instructions.

🧪 Why This Exists

VFC MP7 AEGs are no longer produced and are only available second-hand. This option allows customers to reuse their PolarStar engine and still get a true Bull Craft drop-in solution—without hunting down a donor gun.

You bring the engine.
We deliver the solution.