AIR ARMS TRIGGER ADJUSTMENT FOR THE MODEL S400, S500, S410, S510 and HFT500.
SAFETY WARNING:
-ALWAYS MAKE SURE YOUR RIFLE AND MAGAZINE ARE UNLOADED BEFORE WORKING ON IT.
-CHECK THE BREECH AND BARREL ARE EMPTY.
-NEVER POINT IT AT ANYONE, EVEN IF UNLOADED.
-TEST FIRE ONLY IN A SAFE DIRECTION! EVEN THE BLAST OF HIGH PRESSURE AIR COMING FROM FIRING AN UNLOADED RIFLE CAN DO DAMAGE.
TRIGGER ADJUSTMENTS:
Tools needed:
– 2.5mm Allen key for screw A
– 1.5mm Allen key for screws B and C

Picture 1. Screws A, B and C for trigger adjustment. [Picture from the Airarms S400 manual]
The Airarms S400/410/500/510 trigger has 3 adjuster screws designated A, B, and C in the picture above.
Screw (A) is located in front of the trigger guard and adjusts the weight of pull. Turn it clockwise to increase weight.
When you turn this screw clockwise too much the rifle won’t fire as the spring that sits under this screw becomes coil-bound. But what will probably happen more often is that the screw is turned counter-clockwise too much. Most shooters will want to lighten the trigger pull and then the screw will fall out. As screw A is not a big screw you’ll need to get on all fours and look like a fool to try to find the screw between dust and debris on the floor.
Screw (B) is the front screw located in the trigger blade. It adjusts the first stage (and also total length of trigger travel). Turn screw (B) clockwise to reduce travel.
Screw (C) is the rearmost screw in the trigger blade. It adjusts the second stage by changing the sear engagement distance (how much the both sears overlap each other when the 1st stage is taken up). If the first stage screw (B) is incorrectly set, adjusting screw (C) will have no effect.
TO ADJUST THE TRIGGER
When you only want to increase or reduce the trigger pull weight a little bit you only need to adjust screw (A). Screw it clockwise for a heavier trigger pull and counter clockwise for a lighter pull. You cannot go wrong with this screw. Adjust it in and out as you like, you will see it is easy to get back to the desired or original setting.
Adjusting the 1st and 2nd stage of the trigger is where it gets more difficult as each of the individual screw settings will have an effect on ALL of the settings for weight and length and sear engagement. In other words: when you adjust screw B it will have an effect on the settings of screw C and vice versa.
To properly adjust the trigger first thing to do is to set the trigger to go off on the first stage only. You will feel no 2nd stage.
- Do this by first screwing the 2nd stage adjuster (C) counter-clockwise and well out.
- Then set the 1st stage for desired weight with screw (A) and for 1st stage length with screw (B) to your preference.
- Then slowly turn the 2nd stage screw (C) clockwise until you can just feel the second stage when you pull the trigger. Then give it a further eighth of a turn clockwise for a very light second stage (this may be unsafe!). For a good safe trigger with little or no creep give it a quarter turn or give it a full half turn for a very safe “hunting” trigger.
The final adjustment must always be on the 2nd stage screw (C) as adjusting any of the other screws will change the settings of the first stage and trigger pull.
Make sure to keep your trigger safe. The trigger should ALWAYS return to it’s original forward start position when you have taken up the first stage and then decided not to shoot and let go of the trigger. When your trigger does not return all the way to the front it ‘hangs’. And there it hangs in a dangerous position where it may fire by the lightest bump or touch. Test your newly adjusted trigger by bumping it on the floor while cocked. Do this with a cocked rifle. Also do the bump test after you have taken the trigger up to the first stage but haven not fired it. Do these tests 3 times. Better safe than sorry!
What is inside the Air Arms trigger?

2. Inside the Airarms trigger
The picture above shows an older type Air Arms S400 series trigger. The older types have a trigger blade that freely moves back and forth before reaching the 1st stage. Newer rifles have an extra spring that takes up this free movement.
The older triggers have the rubber o-rings that keep the sears in position on their pins. Changing these o-rings for small washers can give the trigger a better ‘feel’ when done correctly. I have used small brass washers in 3mm (for top pin) and 2mm (for two bottom pins) internal diameter. Put a washer on each side of the sear, top and bottom side, so they lift the sears off the housing. This will reduce the friction between the sear and the trigger housing. Newer Airarms rifles do not need this modification.
I’m not a fan of polishing trigger sears. It is easily done wrong or too much. It may also wear through the surface hardening of the sears. This will then result in much quicker wear of the sear surface and possible unsafe triggers.
Polishing the tops of the set screws is a safer option but I have never felt the need to do that. A properly set up 1st and 2nd stage is all you need. These trigger are really very good when setup in the right way.
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