Sick Cricket, need help!

[jakebbb87]

Hey AGN. My .25 Cricket was avg'g about 870fps with MKII. I have not shot it for a few months, I know shame on me! Anyway, I got a new chrony that is telling me its only sending them at 726. IF the chrony is good, the only thing I can think of is the reg changed during the long rest. It was pressurized the whole time. Any ideas?

Thanks in advance for your input and Merry Christmas!!!

 

[218bee]

I would double check the Chrony with a different known gun thats shooting known velocity. Lighting changes also will change the Chrony results. Just went though this with a match 10m pistol I knew was shooting a certain fps. Pistol was shooting much lower velocity one day. Got better lighting for the Chrony and the results mimicked what they always were.

Ruling out the Chrony, make sure you fill the Cricket to well over 150 BAR. Be sure of pellets too. Doubt its the regulator. I have had many Crickets & Colibris over the years and Kalibrgun regulators seem to be rock solid. Good news is, they are easy to rebuild. Let us know how you make out.

 

[Jammin22]

I would check the HST adjustment, they like to move while shooting. Double check your Chrony. 

 

[bowwild]

That pellet check worked for me one time. I noted here that my Steyr was shooting two different weight pellets the same FPS. I knew that can't be. Someone suggested I check the tins. I weighed pellets from both tins and found out they were the same weights, I had put the wrong lid on one of the tins. A very cheap fix...whew!

 

[jakebbb87]

Thank you all for the advice. I will shoot over my buddies chrono and start there. I have never had any regulator move THAT much. Its a Caldwell Precision Chrony...very mixed review online about this unit.

I appreciate your help!!!!

 

[AirNGasman]

Sounds like you had your Cricket pretty much maxed-out in power, so your hammer-spring might have fatigued or taken a set. Charlie Freer advised me to back-off my hammer-spring (pre-load) adjuster after each shooting session for that reason, and sends a couple hammer-springs with the Crickets he sells.

 

[likkitysplyt]

Per Charlie Frear … "On every Georgia Airgun, I stick a rare Earth magnet on one of the clamp bracket bolts to hold the hammer spring outside the gun for storage, which I recommend it's removal for storage over a week"



A couple of months … I don't know.

 

[zx10wall]

If you must remove the HS from a Cricket to keep it healthy, it’s the only PCP I know of that would require this. It seems a bit goofy to me.

Modern springs should be fine under constant preload. That is unless they are being taken past their yield point. Which, if this is the case, a different more robust spring should be used. 

I’ve seen several HST adjusters mauled up as well as the first threads of the action from folks constantly taking their HS out. I don’t do it but whatever makes you sleep soundly. 

 

[ackuric]

You can use this calculator to determine if your spring is experiencing too much stress per your application, based on minimum and maximum preload of spring plus spring specs. If you are constantly taking your spring to or near max preload, its very likely to fatigue much quicker than one that is only taken to 75% of its max preload. A proper sprung hammer system should ideally spit out Green numbers for the Factor of safety according to Gerber, sines, and goodman, or at least very close to. HTH



https://www.amesweb.info/MechanicalSprings/CompressionSpringFatigueDesign.aspx

 

[jakebbb87]

Thank you all for the great info. I also find it odd that a quality spring would fatigue that much but, after 4 turns inward the FPS did not change. The Cricket platform has been so reliable and easy to tweak. I will test it over 2 chronos then swap the HST if they read the same.

Thanks again

 

[zx10wall]

4 turns is a lot! I think you have something else going on. Once you don’t see a fps increase after an additional 1 turn, you aren’t likely to get anymore speed from more HST. 

 

[Jammin22]

Maybe the HST spring broke?

 

[jakebbb87]

Its not broke and it popped out with a kick. In hand it measures 56.75mm or 2 15/64ths. Is that about right?

 

[zx10wall]

A .25 Cricket spring can be from 2.375 to 2.4 inches long. Yours does seem to be shorter than normal. 

With this said, I have a shorter spring such as yours. I will install it in my non-power tuned Cricket and see what it produces tonight. 

 

[zx10wall]

I tested a non power tuned Cricket that normally can max at 850 fps with the 34s using a factory spring of 2.385” and factory plastic HST adjuster. I installed a shorter HS with a length of 2.15” (I think this is a .22 HS). It maxed at 665 fps using a factory plastic HST adjuster. 

With that news I’d say you do have a sacked-out spring that needs to be replaced. 

When you do get another spring, don’t crank it down. Shoot it over the chrony until you find the plateau max. Find this by adjusting in 1/4 turn increments slowly bringing up the speed. The speed will usually max and then as you dial in more HST it will drop. However, I’ve seen power tuned guns with added plenum tubes not drop but remain the same fps even while dialing more HST. In this case, don’t dial anymore tension if the speed doesn’t increase from an additional full turn of the HST adjuster as you’ve already found the plateau.

You mentioned before that your Cricket could produce 870 fps max. From the max or plateau, back off tension 15-20 fps. This is usually a happy spot for the HS and reg to work well together. 

 

[ackuric]

+1 zx10 seems to be on the ball for ya, I would follow his instructions basically to the tee

 

[AirNGasman]

And FWIW, on my CF-power-tuned .25 Cricket bullpup I decided to see if reducing the power with 34 gainers from 915 FPS / 63 foot-pounds down to 880 FPS / 57 FP might get me the one MOA average (five-shot group) accuracy I seek at 100 yards. It seemed to reduce 'fliers' a bit and increased my shot-count from 52 to 65 shots per 250 BAR charge; so I left her there. Still not getting 1 MOA average five-shot groups at 100 yards, but she consistently averages 1.2 - 1.3".

 

[zx10wall]

Ron, if you haven’t already gotten rid of it, let me know when those first few shots that have a lower fps piss you off enough to remedy it. 

I believe you need to resurface the delrin piston seat in your reg. It’s an easy repair. We could change all your reg o’rings while we’re in there. Strip-down, repair, to back to shooting 34s at 880 would take less than an hour. 

 

[zx10wall]

Jake, I have a spring for you. PM me and I’ll send it to you. 

 

[jakebbb87]

Thank you ZX! I sent a PM. I really appreciate all the great input here.