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Tuning Cricket Hammer Spring Adjustment

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Froggy

Froggy

Member
Sep 17, 2018
58
2
Concord, California, United States
I am new to tinkering with airguns. I recently (this week) had to replace my Cricket Minicarabine WST hammer spring based on what the dealer recommended. This spring replacement was due to a severe fall off of speed from about 850 down to 570. The speed change occurred between shooting sessions one week apart. After searching Airgun Nation and YouTube I was, shall we say, confused. There seemed to be a plethora of hits on my general search parameters of adjusting hammer springs which has led to tough sorting.

For those of you more knowledgeable I am shooting .22 cal. JSB 18.13. When I first adjusted the new hammer spring I picked the following adjustment setting after several adjusted 5 shot strings: - avg speed 874, spread of 4, with std dev of 1. BUT four days later a 10 shot string gave the following: avg speed 839, spread of 16, with std dev of 5. I then did a 14 shot string with avg speed of 844, a spread of 51 and std dev of 19.

Please hear my cry for help in this airgun wilderness. Are there any posts or YouTube videos that you would highly recommend to me. Any and all constructive suggestion are solicited. I just read mcoulter's post about his process. My temperatures were a balmy 60 degrees F.

  1. Original spring 2-3/16” long, replacement 2-7/16” long
  2. Does it take time for the spring to settle in? Didn’t spot any posts that suggested this.
    [/LIST=1]

 
If you are indeed using the factory OEM hammer spring adjuster and didn't get wacky results using them typical popular aftermarket adjusters then probably it's your regulator creeping or faulty. WARRANTY TIME ...

You can even try filling to no more than 2900-3000psi MAX to see if that is a result of the typical filling past 3000psi (even if your guns rated to fill higher) that often gives wacky regulator results and failures too.
 
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Following up on Odoyle's questions, some background might be helpful... 

How long have you had the gun? Are you the original owner? Besides the spring, have you (or previous owners) changed any other parts? I got my 1st cricket (an original .25 cal) used and saw some huge velocity swings in my shot strings right off the bat. ALL of my problems were resolved by changing the gun's springs (plural) AND the hammer spring adjuster back to OEM ones. I had found the previous owners changed both the hammer spring AND the spring inside the firing valve. The funky hammer spring adjuster the gun came with was also binding and causing inconsistent hits on the valve. And sorry if your gun is OEM, then none of this would likely be helpful!

How does the gun sound? Can you hear (or otherwise) sense when a shot is slower? Do you feel any air puffs when you shoot? Have you ever changed the barrel orings (inner and outer)?

Have you tried any long shot strings? I'd suggest doing a string from 200 bar and seeing how the velocity trends. How does the cocking feel? Any grittiness or binding? Is it possible that something foreign got in around the hammer weight? Are all the parts clean and free from any heavy lubricants?




 
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Thanks Odoyle.

The adjuster is an after market one put on by the manufacturer dealer when he sold the new gun to me. I've had the airgun about 9 months with no adjustment and it has performed flawlessly until now. My tests were run after I filled it to about 200 bar (3000 psi). I was wondering about the regulator as you have suggested but don't have enough knowledge to make an educated guess there.
 
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Thanks mcoulter.

I am the original owner. I noticed a definite sound difference and I was not hitting the target anywhere close to where I used to. That is what clued me in to checking pellet speed. Don't feel or hear any unusual puffs of air. I haven't changed the o-rings yet and I have lubed them with silicone occasionally. It was shooting fine one session at the range and the next time it was the pits. I haven't noticed any gritty feel to any of moving parts. 
 
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Gotcha. Is it safe to say that the adjuster is not moving on its own as you shoot? If I don't put a bit of vibratite on the HS adjuster on my .25 to lock it down, it does tend to walk on me (rotates counter clockwise) and lowers my velocity. (My newer .22 cricket's HS adjuster is quite tight and does not change at all.) 

And the aftermarket HS adjuster my used .25 came with was really wacky in that it had an extra weight inside of it. If yours was installed by the dealer, then it's probably NOT like mine and is likely not causing any problems. 
 
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Thanks Odoyle.

The adjuster is an after market one put on by the manufacturer dealer when he sold the new gun to me. I've had the airgun about 9 months with no adjustment and it has performed flawlessly until now. My tests were run after I filled it to about 200 bar (3000 psi). I was wondering about the regulator as you have suggested but don't have enough knowledge to make an educated guess there.
Click to expand...

Put the factory adjuster back I bet you get no problems after that if it's not the regulator acting up. Hope said dealer included the original adjuster if not call him for it it's supposed to come with the gun.

If it's a Donnyfl adjuster fact is there have been hit or miss just like the wobbly threads in the brands LDC custom adapters and LDC threads reported by many already who are well aware and the airgun machinists that mostly won't post anything negative about the brand here.
 
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hammer spring.1609282904.jpg


This is 3 shot strings with the same Hammer Spring setting. (2 - 14 shot and 1 - 10 shot string)

As you can see there is very little consistency between them. It may be as suggested the regulator acting up.
 
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After trying several things including putting back the original hammer spring and adjuster (thanks Odoyle) I took apart the regulator. That is where the trouble lay. There were spots of dried oil film on the regulator piston shaft and on the spring washers. I got out the trusty Dremel and some Flitz polish and it was polishing time. Got the film off the piston and washers in short order. If you do this then be careful not to heat things up to much with the polishing. Cleaned everything, added some silicone lube put it all back together. Took it to the range and it is now working like a champ. It appears that the dried oil film was causing enough occasional extra friction that it changed things.

Much thanks to Odoyle and Mcoulter for their help and suggestions. Cricket is now working better then me.
 
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