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Help me fix my airgun

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J

jackcramerr

Member
Mar 10, 2024
32
5
My airgun stopped working. I cannot pull the lever back in order to get hammer locked. I am keeping thr story short but my current assumption is that the spring is not getting compressed fully. And to confirm this I need help understand the operation of hammer and its spring. Please see the picture.

You can see part of the spring resides in the hammer. You can also see a cutout in the hammer. My question is, should the spring move freely in the hammer? In my case it isn't and the spring part inside the hammer does not compress. The spring is binding. Is this expected behaviour?

Edit: Hammerli AP 40


Item 14 and 15

Thanks.
20240511_225149.jpg
 
Last edited:
Is this out of a break barrel? If you could tell us what model rifle this is out of it would help alot as well. But I'm assuming the hammer and spring sit in a guide rod? If so I would check that and make sure it's in line with everything that moves along the guide, or there may be something that fell out of place that is obstructing the movement of the hammer and spring.
 
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so first off break barrel gun do not have hammer springs
second to all posters details makes the world go round
post the damn make and model of your gun you have a question about so the guessing is held down to a minimum please
a hammer will not lock back on a CO2 and or PCP if when the spring is collapsed before the hammer reaches the sear and or the component of the trigger assembly that holds it
if the gun has an adjuster it is screwed in too far
if the spring has been shimmed it has been shimmed too much
if the spring has been changed and the above is not a factor, the spring is too long
 
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Caliber 22 said:
This look like a pcp hammer. On some rifles, when the hammer spring set screw is turned in to deep the spring binds and don't allow the hammer to get far enough back for the trigger sear to hook onto the hammer.
Click to expand...
Spot on. It is a PCP Hammer AP40. I am not sure what changed and why the spring isn't compressing or if there is something else.

Without the tension from the spring everything else works.

With the tension screw removed, I can use my finger to apply slight pressure to the spring and with just enough pressure I can make the mechanism work. I.e. the hammer moves to the back enough that sear locks it. Increasing the pressure of course results in hammer to be not able to be pulled back enough.

Total length of spring = 33.5mm
Inside length of hammer where spring is inserted = 21.5mm
Part of the spring protruding after installing of spring in hammer= 11.9mm.

When I try to pull the leaver back, the 11.9mm of the spring starts to compress. I can see part of the 21.5mm of the spring from a cut out in the hammer. I can see it isn't being compressed.
 
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marflow 777 said:
so first off break barrel gun do not have hammer springs
second to all posters details makes the world go round
post the damn make and model of your gun you have a question about so the guessing is held down to a minimum please
a hammer will not lock back on a CO2 and or PCP if when the spring is collapsed before the hammer reaches the sear and or the component of the trigger assembly that holds it
if the gun has an adjuster it is screwed in too far
if the spring has been shimmed it has been shimmed too much
if the spring has been changed and the above is not a factor, the spring is too long
Click to expand...
Just posted the details in the original post. At the time I had spent 7 hours straight trying to figure out the issue with full disappointment. Tired and clueless.

It's is a hammerli ap40.

I have not modified the spring.
 
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rc4fun said:
I don't have an ap40. But the spring and hammer should come apart very easy. There should be nothing holding the spring in. Something in the hammer has caused the spring to jam and preventing the spring from compressing the full length. Get a flash light and look.
Click to expand...
I think this is what I wanted to confirm.
The spring is binding. What I don't understand why did it start to happen all of a sudden.

I will try and order a new spring while I get more input from you guys.

I tried to take picture of the hammer's inside but camera is not helping.

20240512_111455.jpg


20240512_110839.jpg
 
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Caliber 22 said:
Did you perhaps adjust the trigger to be lighter and adjust it to much? That can happen as well and it won't cock. I once adjusted a trigger to be very light in cold weather and when it got warm a few months later it would not cock because of the expanding metal working against it.
Click to expand...
No. Didn't make any changes. Story is that there is a training slide in this gun that I replaced. After that I noticed a change in the way loading lever operates. It wasn't smooth. So I again disassembled the parts. Then when I tried to assemble it, came across this issue. I am sure the assembly is correct and it can't really fit any other way.
 
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Try to adjust the trigger according to this site, it might be the trigger adjustment: http://www.pilkguns.com/tenp/sphap40.htm

Trigger Adjustments

Trigger Takeup: To lengthen takeup turn screw 22/6 anti-clockwise.
First Stage Weight: Turn screw 22/5 clockwise to increase first stage weight.
Second Stage Weight: Turn screw 27 clockwise to increase second stage weight.
Sear Engagement: To set sear engagement – cock pistol for dry fire, turn screw 35 gradually clockwise until sear releases. Then back off screw at least 1/8 tp 1/4 of a turn.
Trigger Stop: Screw 51 will act as a mechanical trigger stop. Turn clockwise to reduce after travel.
 
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Caliber 22 said:
Did you perhaps adjust the trigger to be lighter and adjust it to much? That can happen as well and it won't cock. I once adjusted a trigger to be very light in cold weather and when it got warm a few months later it would not cock because of the expanding metal working against it.
Click to expand...
First picture is with the tensioner screw. Notice how everything sits with load lever closed. I have not put the spring for the sear.
20240512_122205.jpg




Second picture shows when I am trying to load it by moving the load lever back. You can see the spring is now allowing the hammer to move back enough for the sear to lock the hammer.
20240512_122300.jpg


Third picture I removed the tensioner screw. You can see the spring protruding. You can also see the sear locked the hammer.
20240512_122404.jpg
 
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jking said:
Is it making contact here (the top arrow)? If it is, I don't see how the sear could drop into the slot unless the angle of the middle piece is changed. Maybe I'm just looking at it wrong though.
View attachment 463871
Click to expand...
Where the top blue arrow points to is a sort of securing ring. It is held onto the pin via a Allen screw. It has enough clearance from the sear. The angle of picture shows it differently. The sear that locks the hammer (top) is at the same level as the one that has the blue arrow at the bottom. The yellow mark in the picture is missing three parts. 1. A washer 2. A spring clip that helps in bring the sear back to its place after the release. 3. A securing ring similar to the one you see in the picture.
Red marking shows where the slot is on hammer.


Screenshot_20240512_215230_Chrome.jpg
 
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sb327 said:
It should just slide in because when springs compress, they grow in od. If it’s tight to begin with, there is no room for this expansion.

The bigger question is what changed? Why is it this way now vs before you made the mentioned changes?

Dave
Click to expand...
That's what I am confused about. What changed do dramatically. One thing I did do was apply some silicone grease. I have cleaned all that since. Can that case the expansion?
 
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Not in my experience.

With the hammer and spring outside the gun, can you compress the spring into the hammer?

In your picture with the spring stop installed and hammer back as far as it will go, the free end of spring doesn’t look compressed (stacked) but it may just appear that way. If the free end doesn’t stack, something else is stopping the bolts movement rearward.

Dave

Circled in red
IMG_5879.jpeg
 
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