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  Fitting instructions for new barrel, hammer or mainspring

Gunpower/Stealth Imperial Allen key sizes ... (not metric !) :

   Allen key sizes :

Trigger pad (1/16"key).

Forend (1/8" key).

Pistol grip (long 5/32"key).

Barrel bush/frame screws (3/32"key).

Bottle retaining ring screw/s, (3/32"key).

Breech slide knob (1/8" key).

Trigger guard (domed socket head screw, 1/8" key).

Gunpower Top-hat grub screws, 1/8"Whitworth thread, (0.050" key).


Removal of the barrel, mainspring and hammer from the front (muzzle end) of the gun

Firstly, make sure there is no projectile in the breech.

Cock the gun (most important*) and do not touch the safety release or the trigger. 

Turn the gun over so the underside is facing you, and remove the countersunk socket head screw which retains the forend using an 1/8" Allen key.

Unscrew the end cap (1) and remove the threaded end cap ring (2) by pulling it out after removal of the 10x32 UNF grub screw (3) which retains it.  This has a 3/32" socket.

The barrel is retained with two or four 10x32 UNF grub screws. Visually locate the two side grub screws (4) if present, and remove these.  (These can be on either side of the gun, or completely absent).   Lying in the channel directly on the same circumference as these, are a further two grub screws (not shown).  It is best to remove these latter screws in a certain order, with the screw closest to the breech to be removed last.

As you remove this last one, hold back the barrel at the muzzle end, with finger pressure to retain the whole barrel assembly inside the frame against the mainspring pressure which you will now be feeling. For the short 12" barrel you will require something similar to a plastic tube to apply this pressure.

When this screw is completely removed, withdraw the barrel assembly complete. 

This comprises the barrel with bushes attached, spring spacer (if present), mainspring and hammer.



The re-assembly is basically the reverse of the above, but with new barrel bushes or stainless steel mainspring, things are a little more complicated.

Start by assembling on the barrel, all the internal components, and obtain roughly the correct alignment for the holes in the bushes with their final position in the frame.

The assembly order is shown below as follows ....  On top of the breech bush (5) goes:

Pretensioning spacers (6) (if required), mainspring centraliser (7), mainspring (8), and hammer (9), with the brass end locating inside the spring, and the chamfered edge facing the breech slide.    

Dry PTFE lubrication can be sparingly added at this stage if required, to the bushes where they engage with the frame, and the barrel mainspring area.  Silicone oil can also be spread on the profiled breech slide area if required, to lubricate the breech slide "O"rings.

Now present the assembly to the frame.

Please note, LCS hammers e.g. the hybrid type shown (9) are barrel guided, and are designed to run dry on the barrel, so require no lubrication.  Please ensure this area is lubricant free to obtain maximum hammer strike consistency. 

My aluminium bushes are a much tighter fit, but at no time must anything be forced.

If resistance is felt, this is because the second bush is not yet in the frame and alignment has not been achieved yet.  Gently rotate or move the barrel until it slides again.

When the muzzle bush (10) is in the frame, and while still holding the barrel muzzle against the spring pressure, I would suggest at this stage you relieve the mainspring tension.  This makes assembly much easier.

This is done by pressing the safety release forward towards the trigger guard, and pulling the trigger.  To prevent damage to the breech slide this must be done while guiding the breech slide rearward against the spring pressure by holding the cocking knob.  You are therefore manually holding back spring pressure at both ends during this procedure, and it is easiest to do this with the rifle held vertically.

When the breech slide is safely engaged with the top hat, (or against the bottle retaining ring if you have previously removed the bottle), you can now push the barrel towards the breech end until a visual line-up is achieved with the two side holes.  It will be necessary to engage the barrel breech with the breech slide to achieve this, and again this is most easily done with the gun held vertically.

With finger pressure only, insert the two side grub screws (4) almost fully, starting with the breech one first, and then gently obtain the thread mate-up with the two tapped holes in the frame channel. When all four screws are located properly, fully tighten them all.

If you have purchased a new LCS end cone for the new barrel to protrude through, insert this into the forward frame opening in any orientation, then insert and tighten the end cap ring retaining screw (3).

Replace the forend.

Care must be taken when locating and tightening this retaining screw as it is easy to cross thread in this position.  If any resistance is felt, the screw has been cross threaded, so must be fully backed out and realigned.

*It is important to cock the gun before stripdown, as sometimes the hammer release detent sear can get caught in the mainspring.  This is not particularly damaging, but the gun will then require a full stripdown of the trigger assembly to rectify this. 

There are five springs underneath the trigger linkage cover plate, most of which fall or spring out as soon as the plate is removed, and the linkages must be assembled in a certain order, so it is best to avoid this.

Finally, and most importantly, please remember to check your power output levels when fitting new components, to ensure compliance with legal limit requirements.
This should be done when changing, adjusting or replacing any component involved in the guns firing cycle, and is entirely your responsibility.  Failure to comply with the law in this respect carries very heavy penalties.

Prosecution for this offence carries a mandatory penalty of five years imprisonment under the Criminal Justice Act 2003.

© DML 2009



 *You will need an Imperial Allen key set for this.*

 These instructions are for the Gunpower Stealth, Storm, Shadow, and Condor, manufactured post 2000.  There are a few design variants for the trigger and safety arrangements in earlier models, so be aware that your gun may differ slightly.

 There are exploded diagrams of the Stealth on my website (Stealth Gallery page 12), which names the parts referenced below. 

All the threads on your gun are either UNF, UNC, or Whitworth and the key sizes on your gun are therefore all Imperial as follows:

   Allen key sizes :

Trigger pad (1/16"key).

Forend (1/8" key).

Pistol grip (long 5/32"key).

Barrel bush/frame screws (3/32"key).

Bottle retaining ring screw/s, (3/32"key).

Breech slide knob (1/8" key).

Trigger guard (domed socket head screw, 1/8" key).

Gunpower Top-hat grub screws, 1/8"Whitworth thread, (0.050" key).

[LCS Top-hat grub screws, M3 thread, (M1.5 key)].


Bottle retaining ring


 1.   Ensure there is no projectile in the breech, and remove the bottle.

 2.   Remove the trigger pad (1/16"key).    

 3.   Cock the gun.   Most important if you are removing only the bottle retaining ring or breech slide, but leave the gun un-cocked for a full stripdown of hammer and mainspring.

 4.   Remove the forend (1/8" key).

 5.   Remove the pistol grip (long 5/32"key) by inserting the Allen key up the handle, and remove the pistol grip retaining stud from the frame.  Please note this stud with the big screwdriver slot does not unscrew!

6.   With the gun inverted, i.e. the underside frame channel facing you, remove the trigger guard (domed socket head screw, 1/8" key).

7.   Remove the trigger plate, and carefully note the spring positions.  (A digital or phone camera can be very useful for this).

8.   Remove the safety reset lever and two safety springs (1 large + 1 small).

9.   Remove the other 3 springs.

10. Remove the bottle retaining ring grub screw/s (3/32"key).

There can be one or two of these and they are always Locktited in position, but with the correct fitting key, removal should be fairly easy.  If you encounter difficulty, heat up the end of your Allen key to red heat, insert into the screw socket and allow the heat to soak into the screw.  Do this at least twice before applying turning force, then you will find removal very easy. (When finished, heat the key to red heat again and quench in cold water to restore the steel hardness).

Breech Slide components


1.   Pull off the rubberised plastic outer cover of the breech slide knob to expose the socket head screw underneath.

2.   With the 1/8" Allen key, unscrew completely, and note the spacer position for reassembly. (Lip in contact with the breech slide).

3.   Withdraw the breech slide through the rear of the frame after the bottle retaining ring has been removed.

3.0  REMOVAL OF THE HAMMER AND MAINSPRING (with barrel still in position) 

1.  Everything as above, (1.0, 2.0) but do not cock the gun at step 1.0.3 above.

2.  Allow the captive trigger linkages to drop under gravity by turning the gun over.

3.  Make sure the hammer retaining sear has fully dropped, and then the hammer, spring and spacers can be removed through the bottle retaining ring hole by shaking the frame.


1.   With the gun horizontal, load your required pretension adjustment spacers, mainspring centraliser, spring and hammer (in that order) onto the barrel.

2.   Push the breech slide onto the barrel (with the trigger sear relief undercut end first), and assemble the spacer (see 2.2 above) and knob, then align this in its frame slot.

3.   Insert the bottle retaining ring into the frame and tighten the grub screw/s, making sure the alignment of the grub screw recess in the ring is correct and mates properly with the grub screw/s before tightening.  Otherwise the bottle retaining ring will be deformed by the screw pressure, and bottle/valve alignment will be skewed.

4.   With the muzzle pointing down and the frame vertical, push down hard on the breech slide against the mainspring pressure, until the hammer nose passes the hammer retaining sear, and then engage this by pushing the sear into position with your fingers to lock the hammer in position.

      Caution … the gun is now cocked !

5.   Turn the gun over so the underside channel is facing you, and align all the various captive linkages, noting that the first trigger linkage and the second linkage interlock.

6.   Place the three vertical springs and the fourth horizontal safety spring in their relative positions. Omit the small safety reset spring for the moment, as this is assembled later.  Please note the three main vertical springs should always be equally spaced when assembled correctly.

7.   Check that the main trigger sear is still interlocked and covered by the second link.

8.   Taking care not to fire the gun, thread the trigger plate over the trigger lever, hold this plate down against the pressure of the three springs, and place the trigger guard in position.  Screw down both almost fully with the button head cap screw.

9.   Swivel the top trigger guard sideways to gain access to the safety reset slot, place the small spring in this horizontally, and cover it with the safety lever.

10. Swivel the trigger guard back into position, and tighten the button head screw fully.

11. While holding the breech slide to only allow a small movement, test that the trigger and safety action is functioning correctly.  When satisfied, it is then safe to un-cock the gun by pulling the trigger while guiding the breech slide and hammer to rest against the bottle retaining ring.

12. Insert the pistol grip retaining stud into its hole in the frame, and use the slot to rotate the stud to obtain alignment with the long socket head screw (with washer on end) passed up the pistol grip handle. Place the end of the trigger guard in the pistol grip, and the pistol grip pip in its location hole at the end of the trigger plate, then tighten fully.

13. Assemble the trigger pad and forend.



This information is provided on an advisory basis only, in order for owners of Gunpower air rifles to service, repair or maintain their equipment within the laws of their domicile country.

This information is not provided with the intention to encourage, promote or allow illegal modification of air weapons, and is to be used entirely at your own discretion and risk.

Whilst every care has been taken in preparation, I can accept no legal liability for the accuracy of this content, or the consequences of any actions taken on the basis of this information, however caused.


© DML 2010


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