In short
- HPA means high-pressure air. A tank feeds air through a regulator and a hose to an engine in the gun, which fires the BB.
- The gain is consistency. Every shot gets the same push, in any weather. It does not buy power: the site limit is the same for everyone.
- The price is a whole system. Engine, regulator, line, tank and somewhere to fill it, on top of the gun itself.
- Expect a lock and a heavy-BB chrono. British sites want the regulator sealed after testing, because the power can be changed by hand.
- Not a first gun. It pays off for regular players who like to tune. A used build is the cheaper way in.
What HPA is
An electric airsoft gun (AEG) uses a battery and a motor to pull back a piston, which pushes air behind the BB, the 6 mm plastic ball. HPA airsoft skips all of that. The air is already compressed, in a tank on your back or on the gun, and a valve lets out a measured puff for every shot.
Because nothing has to wind up, the trigger answers at once, and because the puff is the same each time, so is the shot. That is the whole case for HPA, and the reason it is popular on tuned rifles and on a semi-automatic marksman rifle, what players call an airsoft DMR.
A setup in numbers
- In the tank
- Up to 3,000 psi (pounds per square inch), about 207 bar, on a common aluminium tank
- At the engine
- 60 to 180 psi: the range of the regulator in the picture above
- Through the line
- Plain air, no gas
- Electrics left in the gun
- A small control board and battery that open the valve; no motor, no gears
The parts: tank, regulator, line, engine
Four parts, one job each
Tank
An aluminium or carbon-fibre cylinder that stores the air. Its name gives size and pressure: 48/3000 is 48 cubic inches at 3,000 psi. It rides in a pouch on your back, or screws into the stock.
Regulator
Screws onto the tank and brings the pressure down to what the engine wants. Turning its screw changes the power of the gun, which is why this is the part sites lock.
Line
The hose from regulator to gun, with a quick coupling so you can unplug. It is the part that snags on brambles and doorways.
Engine
Sits in the gun where the piston used to be. A solenoid, an electrically operated valve, releases the air; a control board decides when and for how long.
Engine types
Engines differ in how many valves they use and how they are controlled, but for a buyer the first question is simpler: what does it go into? There are three routes, and the makers build for each. The engines and boards themselves sit with the gearbox and internal parts.
Three ways to an HPA gun
A drop-in engine for an electric gun
Replaces the piston, gears and motor inside the gearbox shell of an AEG. Wolverine sells its Inferno as a drop-in kit for M4, AK and M249 guns; GATE and PolarStar build their own.
GATE in the webshopA conversion kit for a bolt-action rifle
Takes the place of the spring and piston, so you no longer cock a heavy spring for every shot. Wolverine calls its kit the Bolt.
Sniper rifles and DMRsA gun built for HPA
No conversion: the engine is part of the design. The Wolverine MTW and the SIG ProForce MPX HPA are examples. Simple to own, dearer to buy.
Total cost of a setup
We give no amounts here: prices move, and the live figures below are more honest than a number in a sentence. What stays the same is the shopping list, and the gun you convert comes on top.
What you pay for
| Part | Cost class | Worth knowing |
|---|---|---|
| Engine with control board | The largest single item | Fitting it takes skill or a tech you pay |
| Regulator and line | Mid-range | Buy one with a tournament lock |
| Tank | Low for aluminium, high for carbon fibre | Carbon fibre is lighter and holds more |
| Filling | Small per fill, large if you buy your own gear | Ask your site first |
| Retest of the tank | Small, every few years | An out-of-date tank does not get filled |
Used HPA guns on our marketplace right now
A used build usually comes with its tank and regulator.
- listings in HPA on the marketplace
- more than 200
- middle asking price: half ask less, half ask more
- €750
- eight out of ten asking prices fall in this range
- €380 – €1,140
Airsoft Bazaar data Measured on 13 November 2026
UK site rules: tournament locks and joule creep
With HPA, a turn of the regulator screw changes the power. Sites answer that with a tournament lock: a sleeve, cap or cable tie over the screw, so that nobody can adjust it after the test without breaking the seal.
The second issue is joule creep. A heavy BB stays in the barrel longer, the air keeps pushing, and it leaves with more energy than a light one from the same gun. So a gun that reads fine with 0.20 g BBs can be over the limit with the 0.32 g you actually load.
At the chrono with an HPA gun
-
Arrive set for the limit
Set the pressure at home for that site, with the BBs you will play with. People search for the airsoft FPS limit in the UK; sites and the law work in joules.
-
Test with your heaviest BB
The chrono, short for chronograph, reads the speed; speed and BB weight together give the energy.
-
Have the lock fitted
Once the reading is right, the screw is covered and sealed. Leave it alone until you go home.
-
Expect a second look
Marshals re-test during the day. A broken seal usually ends your game.
Joule and FPS calculator
Enter the speed and the BB weight to see the energy. Below is the speed that matches the same energy with other BBs.
Energy
J
The same energy in FPS per BB weight
- 0,20 g
- 328
- 0,23 g
- 306
- 0,25 g
- 293
- 0,28 g
- 277
- 0,30 g
- 268
- 0,32 g
- 259
- 0,36 g
- 244
- 0,40 g
- 232
- 0,45 g
- 219
Calculated with E = ½ × m × v². A site measures with a chrono and sets its own limits; that reading decides.
Filling and testing tanks
A tank is filled from a high-pressure source: a compressor made for it, or a larger cylinder. You find one at sites that support HPA, at paintball sites and at dive shops. Ring first, because not every airsoft site fills tanks. A workshop compressor reaches only a small fraction of the pressure.
- Retest interval, aluminium cylinders
- 10 years
- Retest interval, composite cylinders
- 5 years
- Longest life of a composite cylinder, from its first test
- 15 years
- Highest temperature for a filled cylinder
- 50 °C
Source: Luxfer Gas Cylinders, Cylinder Care leaflet for paintball cylinders; intervals subject to national regulations
Buying an HPA build second-hand
HPA holds its value badly as loose parts and well as a working build, which makes used HPA guns the cheapest way in: engine fitted, regulator and tank often included. Loose engines, regulators and lines are under used HPA parts.
If you look for used HPA airsoft guns for sale in the UK, start with the listings in the UK. Most sellers are in the Netherlands and Belgium, and a realistic gun sent to Great Britain is a sale the seller needs a legal defence for, so expect to be asked for your UKARA number, the player registration British shops check.
Ask before you pay
0 of 6 ticked
Used HPA guns on the marketplace
Complete builds from other players.
Is it worth it for you?
HPA against electric and gas
- HPA
- Electric (AEG)
- Gas blowback
-
Same shot every time
- HPA
- 5 out of 5
- Electric (AEG)
- 4 out of 5
- Gas blowback
- 2 out of 5
-
Trigger response
- HPA
- 5 out of 5
- Electric (AEG)
- 3 out of 5
- Gas blowback
- 4 out of 5
-
Cheap to start
- HPA
- 1 out of 5
- Electric (AEG)
- 5 out of 5
- Gas blowback
- 3 out of 5
-
Little upkeep
- HPA
- 4 out of 5
- Electric (AEG)
- 3 out of 5
- Gas blowback
- 2 out of 5
fewer moving parts, but seals and fittings to watch
-
In the cold
- HPA
- 5 out of 5
- Electric (AEG)
- 4 out of 5
- Gas blowback
- 1 out of 5
-
Freedom of movement
- HPA
- 2 out of 5
- Electric (AEG)
- 5 out of 5
- Gas blowback
- 5 out of 5
the hose and the tank
Should you go HPA?
Which of these sounds most like you?
I play monthly and like to tune
Yes
You will use the consistency and enjoy the setting up. Look at a used build first: someone else paid for the fitting.
Used HPA gunsI play indoors with low limits
Little to gain
At short range a good electric gun does the same job without a hose or a tank.
Compact electric gunsI am buying my first gun
Not yet
Start electric, learn what you like, and convert that gun later if you still want to. Many AEGs take a drop-in engine.
Electric riflesI want gas feel without the cold
Half an answer
HPA cures the cold, but a converted electric gun still has no moving bolt. Some gas rifles can be fed from a tank instead; ask a tech first.
Used HPA partsThree things said about HPA
Myth
HPA guns shoot harder.
Fact
They shoot as hard as the regulator is set, under the same site limit as everyone else. The gain is consistency.
Myth
A light BB at the chrono gives an honest reading.
Fact
With HPA a heavier BB leaves with more energy. Only a test with the BB you play with tells the truth.
Myth
It is fit and forget.
Fact
There is less to wear out, but a tank has a test date and a leaking fitting empties it in an afternoon.
Parts and upgrades in the webshop
Engines, boards and fittings sit with the internal parts.
In stock, ships right away
MR. Hop Up Rubber 70° Silicone for AEG
In stock, ships right away
SP110 Progressive AEG Spring
In stock, ships right away
AA PIANO Wire Steel Spring for AEG - M100Frequently asked questions
What is HPA in airsoft?
HPA stands for high-pressure air. A tank feeds compressed air through a regulator and a hose to an engine in the gun, which releases a measured puff for each shot. It replaces the battery, motor and gears of an electric gun.
How much does an HPA setup cost?
More than most electric guns, before you count the gun you convert: an engine with its control board, a regulator and line, a tank and a way to fill it. A used build with everything included is usually the cheapest route; the live figures on this page show today's asking prices.
Is HPA allowed on UK sites?
At many, on conditions, and each site decides for itself. Expect to be tested with the BBs you play with and to have the regulator sealed with a tournament lock. Ask before you travel, and ask whether the site fills tanks.
What is a tournament lock?
A cover over the adjustment screw of the regulator, held by a cable tie or seal. Once the gun has passed the chrono, the pressure cannot be changed without visibly breaking it.
Where can I fill an HPA tank?
At airsoft sites that support HPA, at paintball sites and at dive shops. Ring ahead: not every site fills tanks, and a filler will refuse a tank that is damaged or past its retest date.
Is HPA worth it over an AEG?
For a regular player who tunes and wants every shot the same: yes. For a first gun, for indoor play or if a hose would annoy you: no. An AEG is cheaper, simpler and good enough for most game days.
Sources
- Firearms Act 1968, section 57A legislation.gov.uk, 12 November 2026
- Firearms (Northern Ireland) Order 2004, Schedule 1 legislation.gov.uk, 12 November 2026
- Cylinder Care for responsible paintballers Luxfer Gas Cylinders, 12 November 2026
- STORM Category 5 regulator; product overview Wolverine Airsoft, 12 November 2026
- Site rules UCAP Airsoft, 12 November 2026
