Author Topic: Tuning with a ssg.  (Read 2373 times)

fmglass

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Tuning with a ssg.
« on: April 19, 2016, 04:23:48 PM »
I am having trouble tuning my gen one mrod with a ssg installed. I'm tired of bothering Travis ( he is great by the way)  but I need to read what other people have done. Give me your settings please. I'm going from 50 psi per shot to 75 psi with very little input from me. Thankyou.
Frank.


  • Geneva,Ohio

Dairyboy

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Re: Tuning with a ssg.
« Reply #1 on: April 19, 2016, 08:27:50 PM »
What caliber and what pellet/weight and what fps are you looking for? Do you have a chrony?
  • Outlook, WA
John 3:16

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.22 JSAR Raptor Mini (on order)
.22 AAA EVOL Tac (on order)

fmglass

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Re: Tuning with a ssg.
« Reply #2 on: April 20, 2016, 05:22:08 AM »
.25 jsb 25.39 im looking for around 850fps. I want shot count over power.
  • Geneva,Ohio

match

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Re: Tuning with a ssg.
« Reply #3 on: April 20, 2016, 07:30:10 AM »
For high shot count get a 6" tube extension... that will help a lot.

Are you using the stock valve? The stock valve has the velocity screw which is used to flatten the tune. But first open it up.

When I tune I fill (hand pump) to the middle pressure of the intended string (I use ~170 bar/2500 psi - you might try a lower pressure) and shoot 4 shots for each setting change.

I do this for many, many combinations to get a feel for the parameter space at the middle pressure.

These 4 shots will become the middle of the string.

You look at the 4 shot string velocity trends and pressures used - comparing the settings.

You want a flat string with low spread - it should not trend up or down.

You are looking for a velocity ~5% higher than your target because you are going to close the exhaust port down a bit with the velocity screw later. About 880-890 fps in your case.

You want low pressure use to get good shot count.

Select the settings meeting these criteria and try them at full pressure (200 bar/3000psi)- running a full string to get the bell curve.

You might also try a slight over fill at this time

Compare the full strings and repeat the best ones a couple times to get better statistics.

Once you have a candidate setting and start pressure - start closing the velocity screw (1/2 turn at a time) and run the strings again.

You should see the bell curve flatten and gain a couple shots at the low end.

It does take a bit of time....
« Last Edit: April 20, 2016, 07:38:54 AM by match »
.40 Badger (arrived!)
.25 Gen I MRod w/WAR valve/SSG & MM custom t-port @ 0.17 (Cothran valve on deck)
.22 1322 upgraded to 2289
.17 Webley Hurricane
.17 Daisy 853
.17 late '60's Crosman Powermaster 760 in the original box

match

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Re: Tuning with a ssg.
« Reply #4 on: April 20, 2016, 07:42:50 AM »
If your velocity or pressure use is erratic try a dry lube in the hammer area and check the ssg for snagging.
.40 Badger (arrived!)
.25 Gen I MRod w/WAR valve/SSG & MM custom t-port @ 0.17 (Cothran valve on deck)
.22 1322 upgraded to 2289
.17 Webley Hurricane
.17 Daisy 853
.17 late '60's Crosman Powermaster 760 in the original box

fmglass

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Re: Tuning with a ssg.
« Reply #5 on: April 20, 2016, 05:52:44 PM »
I  adjust the ssg till I hear air hissing out. Then I back off till the air stops. Then I was adjusting out in small amounts. I went through 6 clips and I'm still using 7 hundred pounds of air for 8 shots. The adjusting nut is turned in showing 9 threads on the bolt. Now what should it try. Keep adjusting the same as I have been?
  • Geneva,Ohio

Dairyboy

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Re: Tuning with a ssg.
« Reply #6 on: April 20, 2016, 06:08:20 PM »
My first guess would be to back out I'd say 2-3 threads on the nut and then try again. When I do the gap adjuster I do it til it hisses as well then once it stops I back out another 1/4 turn and go from there
  • Outlook, WA
John 3:16

.22 SPA M10
.22 JSAR Raptor Mini (on order)
.22 AAA EVOL Tac (on order)

oldpro

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Re: Tuning with a ssg.
« Reply #7 on: April 20, 2016, 07:11:13 PM »
700psi for 8 shots!!! You need way more gap clearence. turn gap adjuster in slowly and softly till it barely touches and then turn back out 1/2 turn.   

fmglass

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Re: Tuning with a ssg.
« Reply #8 on: April 20, 2016, 07:19:42 PM »
Thankyou for all the info. I will try it out.
  • Geneva,Ohio

fmglass

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Re: Tuning with a ssg.
« Reply #9 on: April 20, 2016, 07:20:44 PM »
Thanks Travis.
  • Geneva,Ohio

fmglass

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Re: Tuning with a ssg.
« Reply #10 on: April 21, 2016, 05:19:20 PM »
I got I all fixed up. Travis this thing is great. I'm using 25 psi per shot then I rakn out of daylight. Thank-you to all that helped me out. Now I have to buy one for my daughter's .25 mrod tonight.
  • Geneva,Ohio

fmglass

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Re: Tuning with a ssg.
« Reply #11 on: April 22, 2016, 04:36:27 PM »
I figured out what I was doing wrong. Now I am getting 32 shots using 700psi. I would put up kow many fps but it has been raining a lot so for now I can only put up shots per fill. Thanks for the help Travis. P.S. I ordered one for my gen 2 mrod today.
  • Geneva,Ohio