Tell me about Hammer Spring tension??
My gun is stock. I want to experiment with the HST adjustment some. I have a chroni. what is the best method to get the most out of the gun? and how much difference on FPS can I expect? Thanks. Bill
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This is a good one: http://en.shop.dase.fi/product/47/
FOR 25 cal Cricket shooting around 950fps shooting king.
Valve stem spring 1/2 turn.
Reg pressure 135 to 140b.
HST set at the highest speed.(bottoming out the HST adjuster will not give you the highest speed, most of the time it will lower the speed)
Note: you will need a HST adjuster with a spring guide with no recess. the stock plastic HST has a spring recess so unable to compress the spring further, the threads will bottom out on the action threads. if you turn to far in on the metal adjuster you will unable to engage the shear, the hammer will be hitting the spring guide or fully compressing the spring that will prevent shear engagement)
You my need to add an extra disk to your 16 disk setup, if you try to increase/open the reg pressure above 140b your reg might not close/set.
The 17th disk will get the reg pressure in the 145b+ range in .25 cal producing/pushing it into the 70fpe range …………
~ Greg
I fully second Cricket.
By turning in the adjuster cap, you should get an increase in pellet speed / power up to a certain point, as stated.
Just make sure you don’t strip the plastic cap. For easier adjustment, maybe the purchase of a HST adjuster for the cricket would be an option.
If havimg maxed out with the hammer spring tension screw (plastic cap) and still need more, then it gets a little more complicated, such as increasing regulator pressure (search youtube for “esting rowe”, his videos are very instructive), tuning of poppet valve spring tension and eventually use of a different main spring.
Best is to go step by step, start with the hammer spring tension adjustment cap as stated by our friend Cricket or get and ise special aftermarket HST adjuster.
Keep us updated on your progress.
For best efficiency with your current regulator and valve setup, use your chrony to check velocity while slowly, bit by bit tightening the hammer spring. The velocity will go up until it stops, if you increase the tension more the velocity will go down, this is where you back it off. I would put it right before it levels out the velocity for best air efficiency. So say you start at 860 fps and it levels out at 880 and if you increase more it goes down to 870, back off to 880 and slightly more, maybe 875. Then do a shot string to see how consistent it is. I find the best extreme spread at the “level velocity” but a significant increase in air efficiency (shot count) by backing it off just a little, ES was slightly higher but more shots and not as much muzzle blast.
(Numbers are theoretical)
HI, thanks for the reply. I am using the JSB heavy at around 850 fps. The exacts are at 950. My accuracy is great with the heavy. I just want to bump it up a bit. I have not touched the adjustment. It is the black plastic cap. Thanks. BIll
Hi Bill, doing the same right now, well, the other way round in order to stay whithin legal limits of my host country to be able to use the rifle in my backyard.
No difference in the end, mechanics remain the same.
I try to understand your question. You want to get max speed/power? Or shhot count? A lot of the guys on here tuned the Cricket a bit down for consistency, shot count and to avoid spiralling pellets in some cases.
Some questions to start with:
What exactly is your goal?
Is the hammer spring cap screwed in to it’s maximum? If it’s the plastic cap, turn carefully not to strip it…
What hammer spring is used? Full power?
What pellet are you using (type, weight)?
What speed do you get right now, starting from 200 bar?
What’s the shot count down to 100 bar and respective speed / power (chrony string, maybe even a curve)?
Sorry for a lot of questions, but will help understand your project and where you’re currently standing.
Cheers
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That is the best one, I have them on my 2 Crickets.
But on the 25 cal you might need the extra spring compression guide with no recess, Ernest has them scoll down it’s the one on the right with knurling.
http://ernestrowe.com/accessories
~ Greg