4UAD Magnus Pro AR GBBR Hop-Up Chamber

The 4UAD Magnus Pro is a hop-up chamber for AR GBBRs from GHK and VFC, built with true TDC (top dead centre) adjustment. This means the hop-up pressure is always applied to the same point on top of the BB, however much hop-up you dial in – a marked improvement over standard chambers, where the pressure point moves.

The chamber is CNC-machined from 6061 aluminium, weighs 20 g and is 37 mm long. The hop-up is adjusted through the ejection port with a pointed tool without stripping the gun, and a self-centring tri-lug locking system holds the inner barrel in place. According to the supplier, it fits the GHK without and the VFC with the included spacer. Hop-up bucking and inner barrel are not included.

True TDC hop-up for AR GBBRs

The Magnus Pro makes the hop-up precise and repeatable – two things standard chambers often lack.

• True TDC adjustment: The pressure on the BB moves straight down and always hits the same point, giving more consistent backspin than a rocking standard chamber.
• CNC-machined 6061 aluminium: Stiffer and more precise than cast chambers, so the adjustment does not change during use.
• Adjustment through the ejection port: The hop-up can be fine-tuned out on the field without stripping the gun.
• Self-centring tri-lug lock: The inner barrel is centred and locked, so it cannot rotate and change the trajectory.
• For GHK and VFC: Fits AR GBBRs from GHK and VFC – with or without the included spacer. Combine with the 4UAD GBB Hop-Up Bucking.

Maintenance and safety
Fitting requires knowledge of the gun's internals – if in doubt, have a workshop do it. Always check the gun's velocity after an upgrade so it stays within site limits, and make sure the gun is unloaded and without gas/battery while you work on it.