Classic Army Stoner 96 HPA Gearbox Shell

Classic Army / Knight's Stoner 96 HPA Gearbox

Choose One of 3 Configurations

1. Gearbox Only

2. Gearbox + Nozzle

3. Gearbox + Nozzle + M249 Fitment Kit
     (REQUIRED if using a standard / NON-M249 PolarStar F2 or Jack)

⚠️ IMPORTANT COMPATIBILITY NOTICE — READ BEFORE PURCHASE

This gearbox is NOT compatible with the PolarStar V2 Trigger Board due to interference between the body pin and board placement.
➡️ We have removed V2 trigger board support entirely to prevent install issues and customer frustration.

💡 Critical Note for F2 & Jack Users

If you are running a standard (NON-M249) PolarStar F2 or Jack, you MUST select the option that includes the M249 Fitment Kit.

The M249 Fitment Kit includes:

• Plug Board

• Bullet Valve Lead

• Trigger Switch (included as a backup if your build is missing one)

❌ No kit = improper fitment
❌ No kit = alignment issues
❌ No kit = unreliable operation

If your engine is M249-specific, you do NOT need the kit — those parts ship with the engine from PolarStar.

🔧 Product Overview

Upgrade your Knight’s or Classic Army Stoner 96 with a purpose-built Bull Craft HPA Gearbox, engineered as a true drop-in solution for PolarStar engines. Designed to eliminate guesswork, shims, and alignment headaches, this gearbox locks everything where it belongs.

✅ Core Features

• Dual nozzle alignment points for precise tuning

• Updated specifications based on tech testing and customer feedback

• Built-in compatibility with PolarStar F2 & Jack

• No shim kit required for engine installation

🔥 Nozzle Requirement — READ THIS

• PolarStar F2 & Jack require the #3 M249 nozzle

• Select the Gearbox + Nozzle option if you don’t already have one

🛠️ Hop-Up Modification Required

To ensure proper BB feeding:

• The hop-up window must be elongated/opened

• This has been required on both Bullgear and OEM hop-ups

This is a known and expected step for proper function.

🆕 NEW DESIGN FEATURES

• Front-side wire & FCU pass-through for clean routing

• Rear FCU cavity for organized rear wiring

• Precision-aligned front pin — no shims needed for Jack or F2 installs

Built for our gearbox.
Built for PolarStar.
Built to work the first time.