Cricket .25 tuning: Keep playing or be happy?

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mcoulter

mcoulter

Member
Dec 16, 2015
1,175
118
Syracuse, NY, USA
What is the potential for a .25 Cricket with a plenum extension? Here's my latest string with JSB 33.95 pellets.

  • 48 shots
  • ES 15 fps (1.76%)
  • Starting / ending pressure = 225 bar / 130 bar
  • Avg fps / fpe = 843 / 53.7
  • Efficiency = 1.27
  • Hammer spring at 6 turns

The gun feels and sounds quite good. I'm just wondering if it is worth setting the reg a bit higher. The huma is set at 120, but the gun shows a drop in velocity right after shot #48 which was 130 bar according to the gun's gauge (shot 49 and after went like this 839, 840, 836, 834 so I think it's clear we have a 10 bar discrepancy between the regulator's label and the gun's gauge). 

https://photos.app.goo.gl/wLeBNd5skxXuVhR87

1590507064_9330481065ecd3638ba09c5.71644604.jpg




And for reference, this is where I am in the hammer spring adjustment with my current reg and firing valve settings:

1590507534_7118130015ecd380ed982f2.20595213.jpg




FWIW, this velocity (in the 840s) works great with the JSB 33.9 MKIs but the MKIIs don't perform quite as well at that speed. I'm wondering if a bit more velocity is needed for the MKIIs... 

Thoughts?
 
Generally a barrel either prefers the mk l or mk ll...as they are both the same weight, if you're shooting the mkl's great, why bother with the mk ll's?



Beyond that I can't recommend higher reg setting being that you didn't state your plateau, or at the least how far from plateau you're currently tuned.



Running it around 3-5% from your peak velocity should be your goal. Your efficiency isn't low but its not high either at that power level...if its a 19.5" barrel it explains the efficiency a bit, if you're running below ~.2" porting it explains it even more. With that plenum volume you should be able to get better efficiency unless its barrel length / port od. Based on that number alone (efficiency), you're likely too close to peak/plateau and should A) turn up reg a bit more or B) turn down fps some/less hammer strike.




 
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Thanks for your input folks.

@Zeringue - Thanks for the info on your Dad's cricket. As a little back story my gun actually came shooting just about that hot. However, it had kind of a wacky hammer spring adjuster that had an extra weight with it. As I was sorting through some binding that was caused by that accessory, Charlie actually chimed in with a warning regarding that setup my gun had might not be the best thing for the receiver block.

@ackuric - Why bother with the MKIIs? That's a great question... I guess this is exposing just how much I like tinkering and testing. I would really enjoy discovering if I can safely get the 33.9 JSBs to 920 fps without making permanent mods (i.e. porting) to the gun. It's really just curiosity of wanting to test these pellets across a decent range of velocities that I'm aiming for now. Regarding the velocity plateau, at 6 turns I am about 10 fps below the plateau which happens at 7 turns. (Earlier HS testing showed no gains at 8 turns.) Next time I take the shroud off I'll measure the barrel. I have to admin that I don't know it's length. (BTW, the shroud was a pain to twist off.)

@cmatera - Yeah, I'm with you. I don't hunt so this is really just an effort to explore the range of velocities this gun is capable of to further test accuracy at what ever speed I can. FWIW, this is the first pcp I have had that is this easy to adjust the hammer spring. Every other gun I had to remove the stock to get to the HS adjuster.

Ideally I'm hoping to find the optimal speed for the 33.9 JSB and then be able to know what HS adjustment to make to shoot the kings reasonably well when I'm just wanting to hit spinners :)
 
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My point in asking why bother with mk ll's is that you said the mk l's shoot great...and are the same weight...if you have a 33.95 gr pellet shooting great why be bothered with if its the mk l or mk ll?



If an mk ll doesn't shoot well for you at 840 but a mk l does, I doubt bringing the mk ll up in fps will work out any magic to make it suddenly shoot better than the mk l while doing the same...so if I were you I'd work with the mk l's is all I am saying.
 
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My point in asking why bother with mk ll's is that you said the mk l's shoot great...and are the same weight...if you have a 33.95 gr pellet shooting great why be bothered with if its the mk l or mk ll?



If an mk ll doesn't shoot well for you at 840 but a mk l does, I doubt bringing the mk ll up in fps will work out any magic to make it suddenly shoot better than the mk l while doing the same...so if I were you I'd work with the mk l's is all I am saying.
Click to expand...

I get it. But I purchased tins of both so I have both MKI and MKIIs sitting on a shelf :)
 
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My 1 1/2 yr old cricket 25; likes 25g JSB. . ES8, SD2. Now, I know that hard to believe. I've checked it over and over. ( gauge in the green, no yellow) fill it in the yellow it doesn't settle into those numbers until you hit green. You can read the print out and the regulator control is clear as night and day,

It CONSISTENTLY out shoots my impact. Its bulky square and definitely not a carry gun for me. But . Accuracy is king. On the bench on the dot.
 
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I put my .25 cricket for sale...because I need it super accurate ,power full, n ultra mouse fart quiet...I wasn't available to find the magic bullet or pellet that could give me what I need it .. the ability to put 5 shoots at 120y on a quarter...so for sale it goes but no body buy it in this round and I just recieved 200 bullet for my regulated talon with the tj .250 liner ..rcbs 25 050 .. so I try them n they fit well shoot them in my shop they cycle great .. so I take it to my home to se how the shoot at a 100y .... whaaaaaaaattt ... that bullet shot awesome a quarter at 120y I was expecting the bullet to drop a lot at 44g --- no jsb -- no Nielsen -- no fx -- no Avs ... a cast bullet....you know that the cricket is going no where and I pay what ever for that discontinued bullet mold ..
 
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