S300/400/500 Series (Inc. HFT 500 & S510 Ultimate sporter)

Main Work 

Regulator & Tune (Includes a full service)

The Regulator & Tune packages are designed to make your rifle more consistent and air efficient, not more powerful. All sub 12 (non FAC) rifles are set to around 11.5ft/lbs after any work is done, keeping you well within the legal limit.

When the work is done by the RAT Works the action is extensively worked on to increase the performance, efficiency, accuracy and overall feel of the rifle. Almost every aspect of the rifle is modified, changed or enhanced in some way.

Air Arms

Fill Pressure when Tench Regulated







S4/5*0 Carbine




S4/5*0 Rifle








Below is a list of all the work undertaken as part of the tune.

Hammer Mechanism

- Ensure the assembly is free of any oil, grease or debris which can cause consistency issues

- Re-finish hammer spring to a higher accuracy

- Polish the bearing surfaces in the hammer

- Hammer/trigger sear mating face is modified if needed

- The Hammer spring is considerably shortened to reduce the power after the regulator is fitted, this makes cocking effort much less and puts much less pressure on the trigger sears, allowing a much crisper and responsive second stage.

Loading assembly

- Loading probe modified for pellet feed and smoothness

- Bearing surfaces polished

- If you include the magazine in with your rifle they are also modified to remove any loading issues such as jamming whilst cycling

- Lubricant is added to parts of the assembly to allow a smoother action

- Bolt lock up mechanism is usually modified for more responsive and smoother movement, also increasing the rifles consistency.

Exhaust valve, transfer port & barrel

- The exhaust valve stem assembly is modified to run more efficiently

- Valve body is modified for better airflow through the firing cycle increasing efficiency

- The valve pressure is reset to give a better performance between heavy and lighter pellets

- The transfer port is modified to give a higher degree of air flow efficiency

- Crown of the barrel re-cut or polished if needed to increase the rifles accuracy

- Transfer port and barrel are aligned correctly

- The Adjuster in the transfer port is set with minimum restriction to allow a much more efficient use of air, 90% of the power setting is done with the hammer spring shortening. Only the final setting is done on this adjuster, which also helps with the FPS variance.

Trigger assembly

- Sears are polished to a smoother finish if needed

- Hammer engagement sear modified if needed to smoother let off

- Trigger let-off is set to a comfortable and safe amount.

Some parts may be chargeable although I do replace many damaged parts for free as standard. 

O-ring seals are replaced as standard throughout the rifle and refitted with the correct lubrication.

After the regulator is fitted and the tune carried out you can expect a shot to shot consistency of single figures as soon as the rifle has been worked on. A report sheet will be included with the rifle once work is complete detailing the shot to shot consistency through our SKAN chronograph, the rifle is held correctly in a mount to guarantee accurate results.  This consistency will improve further as the rifle is used.

Full Service 

The full service strips and rebuilds your rifle replacing all seals and renewing any worn parts to revamp performance while sorting any problems you may have such as leaks, low power, poor shot count or other faults.

Important Gauge Information!

Once your rifle has been fitted with a regulator, the original fill gauge will read regulator pressure and not fill pressure. This is due to the location of the regulator and the standard gauge.

If you require the ability to read fill pressure from your rifle please select the "Quickfill & Gauge" option.

Safe practice is to always obvserve the gauge on your air bottle/dive bottle and ensure that when filling your rifle that the gauge reading does not exceed your rifle's safe working pressure.

Rifle Collection & Return Service

We can arrange a collection and return service from you via our fully insured next day courier if you are not local to us. This service allows air rifles to be collected and returned to your home address on a fully insured next day service.


1. We will only need the action/metalwork of the rifle, no stock, silencer, scope or shroud etc.

2. If applicable, please include the magazines or magazine you prefer to use with the rifle, if you have ever had any problems with them and we can investigate as required.

3. Please ensure the rifle is not cocked or loaded when packing for shipping! Rifles can still be charged with air.

Do not ship in a case/bag or with stock on(except for stock engraving or spring rifles) Shipping with these will incur a £25 storage/re-shipping charge.

5. Pack the rifle in a plain, strong cardboard box preferably with adequate newspaper or bubble wrap packing and mark the box with FRAGILE and DO NOT AIR UPLIFT.

6. Collection can take place any time between 09:00 and 18:00 on the day, we cannot specify a time unfortunately.


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