Cricket BP hammer spring not consistent

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mcoulter

mcoulter

Member
Dec 16, 2015
1,175
118
Syracuse, NY, USA
Hi folks,

I picked up a used .25 cricket bp recently. I have found that it's not giving a consistent hammer spring hit. Sometimes while cocking it it gives a noticeable grinding feeling and that shot will be way slower than the rest. I have tried a range of adjustment settings and so far I have not found a sweet spot that gives consistent strikes. Here's some pics. I did a quick disassemble of the hammer spring, cleaned it out and this really didn't help much . I'd love to get some input from folks on what to look for. I expect I'll be opening up the side cover next to inspect what's in there. This is my 1st cricket so I am trying to go slowly in taking it apart and playing: 

1576362668_2524140135df562aceb8890.83515061_IMG_20191214_145208.jpg




1576362738_3697626945df562f2e92e66.52821230_IMG_20191214_103908.jpg




1576362862_18077599265df5636e15b2e2.14871775_IMG_20191214_114015.jpg




There was some pretty significant galling/scratches on the adjuster pin which I was able to polish out:



1576362901_18934552845df56395b16a50.00566850_IMG_20191214_110911.jpg




1576362970_13973236985df563da63f237.38911363_IMG_20191214_114026.jpg


Even with the wacky velocities it's accurate as heck. 36 shots in 3 nice groups (only 33 yards for now):

1576363137_8975164655df5648158aae9.26229267_IMG_20191214_124216.jpg




And it is purdy..



.
1576363233_3120938495df564e102d015.69984430_00100lrPORTRAIT_00100_BURST20191214124343517_COVER.jpg



 
Matt, that piece that looks like a nail is something I have never seen before in a Cricket. It appears to be an added weight to make the striker hit harder. It has been my experience that an added weight or a stiffer spring will eventually lead to the aluminum receiver failing. The grinding you are feeling is a precurser to that failure. I would strongly suggest you remove it. 

A properly done powertune does not need a higher reg setting, a stronger spring or an added weight.

My current powertunes are going out with a factory reg setting of 110 bar and a .22 cal hammerspring which is five millimeter's shorter than a .25 cal spring. Added power can be obtained with better airflow tuning.

I hope it is not to late for your receiver.

Charlie Frear, Georgia Airguns
 
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I'd recommend cleaning out and polishing the "tunnel" that the hammer travels in. If there is any oil or grease in there is will adversely affect the consistency of the hammer strike. Never lubricate that area of your gun. Clean it out, polish it, then reassemble. I've had the same issue before and it turned out the area had some grease and dirt in that part of the gun. I agree with Derrick, nice adjuster, and you have the Power Plenum, looks like the gun was power tuned at one time... 
 
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That’s a nice hammer spring tension adjuster. The gun looks to have an added plenum. What projectiles are you shooting? What does the gun max at in fps at you current reg setting and what speed do you have it set for with the HS tension adjuster?
Click to expand...

Hi there 

Thanks! I googled this a bit and have not seen any adjuster quite like this one. I have no idea where it came from. On that note, what gives away the added plenum? At three turn out on the HS, it was shooting Air Arms 25.4 at just over 1000 fps. At what was lesser HS tension I would see a velocity range from 804 fps to 896 fps with the same pellets. 

After fiddling with it for while I decided to see if I can determine a baseline for HS settings. I found that I could cock and fire with the HS at max. I then tested at 1, 2, and 3 turns out. Then filled the gun again to 220B and shot more at 3, 2, 1 turns. Sorry for the crappy pic here. This data is at the bottom of this pic. The binding and slow velocity was pretty bad on the final set of 3 shots.

NOTE: the speeds here at in MPS. I gave some baseline numbers to convert around the strings. (Light was terrible so I had to use my aliexpress chrony that is lighted)

1576368248_6110968515df5787820d151.16201980_IMG_20191214_151104.jpg





 
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Matt, that piece that looks like a nail is something I have never seen before in a Cricket. It appears to be an added weight to make the striker hit harder. It has been my experience that an added weight or a stiffer spring will eventually lead to the aluminum receiver failing. The grinding you are feeling is a precurser to that failure. I would strongly suggest you remove it. 

A properly done powertune does not need a higher reg setting, a stronger spring or an added weight.

My current powertunes are going out with a factory reg setting of 110 bar and a .22 cal hammerspring which is five millimeter's shorter than a .25 cal spring. Added power can be obtained with better airflow tuning.

I hope it is not to late for your receiver.

Charlie Frear, Georgia Airguns
Click to expand...

UGH... that piece was machined so well I did not expect that it was not original. Can you (or anyone) give me the specs on the standard spring? Unfortunately, I don't have the original parts. Can anyone measure the length of the standard adjuster so I can compare to my parts? I have not cracked into the air tube or regulator so I have no idea what it is set at.

1576368708_272939495df57a445219c2.60843670_Cricket-WB-cal.25.jpg

 
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I'd recommend cleaning out and polishing the "tunnel" that the hammer travels in. If there is any oil or grease in there is will adversely affect the consistency of the hammer strike. Never lubricate that area of your gun. Clean it out, polish it, then reassemble. I've had the same issue before and it turned out the area had some grease and dirt in that part of the gun. I agree with Derrick, nice adjuster, and you have the Power Plenum, looks like the gun was power tuned at one time...
Click to expand...

Yup, I tried to do that. It was a bit gunky. I cleaned out what I could and left it dry. Can anyone advise on what's behind the side plate? Can it be removed to (minimally) inspect it without something going "sproing"? 
 
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Had that same adjuster and had the same problem. It's supposed to stick out the back to indicate when the rifle is cocked, but it seemed to bind a lot. Probably could have been fixed, but I ended up throwing it away and got one from Ernest. AOA has them too.
Click to expand...

OK, that's good to know. And yes, it does give a visual when the gun is cocked by protruding out the back.
 
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Right off the bat I recognized that the reservoir was longer than factory. Looking closer, I see a bit of the shiny added plenum toward the action side. 

That hammer spring tension adjuster can be purchased from eBay. The seller is from the U.K. Although it looks great and is made from stainless steel, as Charlie alluded to, the spring guide is also being utilized as a hammer weight.

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F153501775178

As nice as it is, I’d discontinue using it or modify it so as not to have a hammer weight. 

Are you wanting to continue to shoot the 25.39 gr or the 33.95 gr pellets? 

PM me and we can exchange contacts. I have what you need and can guide you through doing the work yourself. 
 
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Thanks to everyone who has chimed in here! It's clear after reassembly and a little more shooting, that there's a burr on one of the ends of the hammer spring that needs to be filed down. It did not take many shots for the gouges that I polished out to reappear on the spring guide/weight piece. No doubt this is affecting the hammer spring and valve impact consistency. My plan is to return this to a baseline with an OEM spring adjuster and get a good baseline on the gun. :)
 
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I received the new hammer spring adjuster today. It feels really good in the one magazine I had time to shoot. I gave it a total guess at how much to turn it in, but I came out with a consistent 49 fpe with the air arms 25.4 grain pellets (935 fps). I can't wait to see how it performs over longer strings!

Update: I shot a long string (60 shots) and while it still needs some work, it is cocking MUCH better and is more consistent. I got about 43 good shots before the surge in velocity. Next up is some further testing of where I am in my HS adjustment range.

https://photos.app.goo.gl/aZVCGJQYiqqULj6J6

1576955369_21064642025dfe6de9a29b13.45324722_12-21-2019 cricket 60 shot string new HS.jpg

 
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I did some further hammer spring testing and found that with Air Arms 25.4 grain pellets it maxed out at 995 fps (just under 56 fpe). I backed off two turns on the hammer spring and it's now shooting them at 970 fps (53 fpe). At this setting it's shooting JSB 34 grain MKII pellets at 890 (just under 60 fpe). I'm running low on pellets so I'll have to wait until my pellet order arrives on Monday to do some longer shot strings and accuracy testing. But so far I'm a very happy camper :) Thanks for help everyone! 
 
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