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PolarStar Hop Up Thing — CNC V2 Hop Unit for AEG and HPA

PolarStar Hop Up Thing — CNC V2 Hop Unit for AEG and HPA

£84.95
£84.95
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DETAILS

SKU: 77139322
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PolarStar Hop Up Thing. A CNC-machined hop unit for standard V2 M4 and M16 gearboxes, running either an AEG or an HPA engine. 6061 T6 aluminium cut in-house to a two-thousandth of an inch, with PolarStar's TDC slider doing the adjusting.

Hop units are where accuracy is won and lost, and most of them are cast parts that arrive slightly off-spec and loose in the barrel. PolarStar machine this one themselves from 6061 T6 aluminium to a tolerance of two thousandths of an inch, and the reason that matters is fitment: a unit that sits snug in the outer barrel and square to the gearbox face cannot rotate or creep, and a unit that cannot move puts every BB on the same line.

The adjuster is the part worth understanding. Older sliders push the nub from an angle, so they drift under vibration and lose their setting over a magazine. PolarStar's TDC — top dead centre — arm applies pressure straight down through the centre line of the barrel instead. Vertical pressure on the nub gives a flight path that stays where you set it, and it takes the common 3x4mm nub rather than something proprietary.

The design is modular so the same unit suits both an AEG and an HPA build, and PolarStar make a short line of parts for tuning it further: alternative gearbox lips in tighter inner diameters to stop a nozzle deflecting, barrel slot bushings to take out rotational play, and a fine adjustment ring that halves the sensitivity for R-hop and flat-hop setups. Those are separate items and our supplier does not currently carry them — ask us if you want one sourced direct.

Specifications

Specification Detail
Compatibility Standard V2 M4 / M16, AEG and HPA
Material Machined 6061 T6 aluminium
Machining tolerance Plus or minus 0.002 in
Adjustment TDC slider system
Nub compatibility 3 x 4 mm
Gearbox lip supplied 0.305 in, standard for most AEG nozzles
Colour Batch 01, Medical Metal Gray
Manufactured Made in the USA
In the box Hop unit, 0.305 in gearbox lip, 3x4mm round nub, axle retaining O-ring tool, five shimming O-rings and a moulded barrel clip
Brand PolarStar

Good to know

Which gearboxes does it fit? Standard V2, which covers M4 and M16 platforms. It is not a V3 part, so an AK will not take it.

Is this an AEG part or an HPA part? Both. PolarStar list it for AEG and HPA builds, and the fitment is modular so you can tune it to either.

What is TDC and why should I care? Top dead centre. The arm presses the nub vertically through the barrel's centre line rather than at an angle, so the setting holds instead of wandering as the gun vibrates.

Can I keep my own nub and bucking? If the nub is a 3x4mm, yes. The supplied lip suits a typical AEG nozzle; a narrower engine nozzle is better served by one of the tighter lips PolarStar sell separately.

Do I need the Direct Attachment as well? Only if you want to mount an F2 or JACK engine straight onto the hop unit and do away with the upper shell. As a straight hop unit replacement this works on its own.

⚠ Fitment is the whole point: measure your outer barrel slot before assuming a drop-in. A hop unit that is loose in the barrel undoes everything the machining buys you, which is exactly what the bushing set exists to fix.
💡 Titan Forge Airsoft tip: It pairs with a good bucking and a matched nub — both sit in our spare and upgrade parts. If this is part of a conversion, our HPA tech service can build and tune the whole gun.