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BullCraft Tech Support / VFC MP7

HPA MP7 Support & Troubleshooting

Installation, maintenance and common fixes for BullCraft HPA conversion kits built for the VFC/Elite Force AEG MP7. Choose what you need help with and go directly to the correct guide.

  • VFC / Elite Force AEG MP7
  • Gen. 2 & Gen. 3
  • PolarStar JACK & F2

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What do you need help with?

Select the description that most closely matches what you are doing or experiencing.

Video Guide Library

Installation, fixes and maintenance

Each video loads only when selected, keeping this page fast on desktop and mobile.

Guide 01 / Installation

HPA Gearbox Installation

Installing a BullCraft drop-in kit or reinstalling the gearbox after receiver service? Start here.

Use this when
Completing the initial kit installation or reinstalling the complete gearbox assembly.
Pay attention to
Trigger and selector placement during receiver reassembly.
Applies to
BullCraft VFC/Elite Force MP7 HPA drop-in kits.
Open directly on YouTube

Guide 02 / Firing

Double-Firing Solution

Use this guide when one trigger pull produces two shots or more than one firing cycle while set to semi-auto.

Symptom
The MP7 fires twice on semi-auto instead of producing one shot per trigger pull.
Expected result
One complete firing cycle for every deliberate trigger pull in semi-auto.
Applies to
Drop-in kit installations and completed BullCraft HPA MP7 builds.
Open directly on YouTube

Guide 03 / Controls

Selector-Switch Adjustment

Use this guide when the selector positions do not line up, fully engage or correspond with the intended firing mode.

Symptom
Safe, semi-auto or full-auto does not engage correctly after installation or service.
Use it after
Installing the gearbox or any service that required removing the selector components.
Expected result
Each selector position engages positively and corresponds with the correct function.
Open directly on YouTube

Guide 04 / Maintenance

Hop-Up Access & Maintenance

Follow the correct disassembly sequence when accessing the hop-up unit, bucking, inner barrel or hop-up arm.

Use this when
Cleaning, inspecting or replacing components in the hop-up and barrel assembly.
Service advantage
The hop-up and bucking can be accessed without a complete gearbox teardown.
Before opening
Disconnect the air line and FCU battery, remove the magazine and clear the chamber.
Open directly on YouTube

Need More Help?

Still not running correctly?

If the problem continues after following the appropriate guide, send us the information below. The more we can see up front, the faster we can identify what is happening.

Include with your request

  • 01Order number
  • 02Drop-in kit or complete receiver
  • 03PolarStar JACK or F2
  • 04Receiver generation, if known
  • 05Regulator PSI and BB weight
  • 06Current FCU settings
  • 07A short video of the problem
  • 08Which guide you already followed