CNC Hop-Up Chamber AR15 BASIC by RetroArms

The AR15 BASIC hop-up chamber is a high-performance unit from Czech manufacturer RetroArms, designed for AEG replicas based on the AR15/M4 platform. The body is precision CNC-machined from EN AW 7075 aluminum. The chamber inlet features an O-ring that prevents BBs from falling out during reloads. The collet nut ensures barrel centering and eliminates unwanted movement, regardless of the outer barrel diameter (compatible with 8.4–8.5 mm barrels). The BASIC version is the easiest to install, requiring no adjustment to nozzle length or gearbox alignment. It’s also fully compatible with most hop-up buckings.

Comparison of BASIC, PRO, and ULTRA Hop-Up Chamber Models

1. BASIC
   Perfect for users seeking a reliable and accurate chamber without fine-tuning. CNC-machined from EN AW 7075, features an O-ring to prevent BB drop and a collet nut for barrel centering. Ready for R-hop and compatible with most buckings and barrels. Excellent performance-to-price ratio and simple installation.
   
   
2. PRO
   Based on the BASIC model but adds an adjustable magazine well height in 0.2 mm increments, improving magazine compatibility in some AR15 setups. Includes the same collet nut, O-ring, and CNC construction. Ideal for users who need precision and consistent feeding even with tricky mags.
   
   
3. ULTRA
   For demanding players seeking a fully tunable chamber. Adds longitudinal adjustment relative to the gearbox. Features an enhanced barrel locking system with a POM lock and clamping nut to eliminate movement. Also includes a flat, extended bucking channel ready for ROBUST no-lip buckings. ULTRA is the most advanced model in RetroArms’ lineup.

Key Features

• Durable EN AW 7075 construction
  Maximum strength and precision thanks to CNC machining.
  
  
• Collet nut for barrel centering
  Prevents barrel movement and improves shooting consistency.
  
  
• O-ring in chamber inlet
  Prevents BBs from falling out during reloads.
  
  
• Improved compatibility
  Works with most hop-up buckings and 8.4–8.5 mm inner barrels.

Technical Specifications

• Material: Aircraft-grade aluminum EN AW 7075 (CNC machined)
• Chamber type: AEG for AR15/M4
• Chamber inlet: With O-ring
• Barrel locking: Collet nut (for 8.4–8.5 mm barrels)
• Compatibility: Tokyo Marui AEG standard (most hop-up buckings)

Package Contents

• CNC Hop-Up Chamber AR15 BASIC
• Collet nut