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GTA ARK (Airgun Repository of Knowledge) Airgun Content Achives => Airgun Content Creator Videos => Hajimoto Productions => Topic started by: scion19801 on March 22, 2020, 12:23:05 PM
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Can you or anyone give me the spec on the Poppet outer diameter from the ST kit? I have mine all installed and forgot to measure it. Found a neat spread sheet calc and it needs poppet diameter. Thanks
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Can you or anyone give me the spec on the Poppet outer diameter from the ST kit? I have mine all installed and forgot to measure it. Found a neat spread sheet calc and it needs poppet diameter. Thanks
The poppet has a step and has a large OD of 0.338" and the smaller dimension is 0.197".
The height of the larger OD is 0.310" and the height of the smaller OD is 0.118"
Hope this helps
Haj
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thanks haj. you rock man. gauntlet is coming along nicely. seems a bit odd that i have to crank my stk in 8+ turns from flush out to get to 888 fps. I know ports need to be opened up. i did do the barrel to 11/64". It there a better or aftermarket valve system that would fit, so i dont have to worry about messing up a hard to get factory unit?
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thanks haj. you rock man. gauntlet is coming along nicely. seems a bit odd that i have to crank my stk in 8+ turns from flush out to get to 888 fps. I know ports need to be opened up. i did do the barrel to 11/64". It there a better or aftermarket valve system that would fit, so i dont have to worry about messing up a hard to get factory unit?
Don't get caught up in the "amount of turns" game. All that matters is that you gain more FPS than stock and more shots. The turns in per Gauntlet are always different. I have tuned 100's of Gauntlets and no two are the same. I produce a chart like what is below for every one I tune. There really is nothing you can do to destroy the stock valve unless you do something rookie.
(https://i.imgur.com/BvveFTV.jpg)
Hajimoto
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ok. so you count turns in 180 degree increments. i was counting in full turns. i know i started off flush put on one turn checking each shot over my prochrono and stopped once i saw speed no longer increase, backed off one turn and used 1/4 turns to bring back up to my target speed.
this is my first time modifying an airgun, but im very technical and detailed. been an automotive tech for 20 years to i know my way around tools of all manner.
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ok. so you count turns in 180 degree increments. i was counting in full turns. i know i started off flush put on one turn checking each shot over my prochrono and stopped once i saw speed no longer increase, backed off one turn and used 1/4 turns to bring back up to my target speed.
this is my first time modifying an airgun, but im very technical and detailed. been an automotive tech for 20 years to i know my way around tools of all manner.
HUH?? 180° is a half turn as is captured in the chart. Every 360° of rotation is 1 turn.
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LOL. yeah i realized that after looking again at it. it wouldnt let me modify as too much time had past. got to look at things closer before posting. It's all good. sorry
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bunch of testing today. reset my stk. and made a chart like the one above. can't wait for my larger bottle to get here. this things should be a monster on the flex regulator. i'm currently set at 1850-1900 psi on the regulator. 11-1/4 turns in from flush slinging Air Arms 25.4 gr at 890 fps. At 12-1/2 turns in, slinging 33.95 gr JSB MK2 heavy at 834 fps. so i'm at 43.5 fpe with the Air Arms and a whopping 52.5 fpe with the MK2 heavies.
This is with only the new poppet and only porting the barrel. cleaned up leade, and new probe orings. the ( McMaster Carr part number ZMCCH90M1.6X3.1) seem to be working well.
Now to see where the groups are and if its happy at those speeds.
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Gauntlet .177 and .25. Using a .45l bottle now. If I swap out the lower pressure rupture disc for a PI on the reg. Will it display the output pressure of my reg? Is there an equation to calculate output pressure of regulator? .
177 - 10.5gn at 1050 fps I think it should be more but Im having pellet probe oring issues with .177.
.25 - 28.24gn h&n barracuda hunter extreme at 925 fps.
And have you had issues with broken belleville washers( only the black ones)?
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don't do it. the rupture dik is a fail safe device. you need to build a regulator tester to setup the pressure output of the factory regulator. Or just get the flex regulator that will show you both the tank and regulator output.
Yes over time the belleville washers will flatten out if put into too much overstress situation. they would then need to be replaced of heavier ones put in place to handle it.
What issue are you having with pellet probe o'rings? If they're getting chewed up then the mags need cleaning/deburring work. or it could be the chamber side of the barrel needing to be crowed so that it isn't a sharp edge for the o'rings to slide across.
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Gauntlet .177 and .25. Using a .45l bottle now. If I swap out the lower pressure rupture disc for a PI on the reg. Will it display the output pressure of my reg? Is there an equation to calculate output pressure of regulator? .
177 - 10.5gn at 1050 fps I think it should be more but Im having pellet probe oring issues with .177.
.25 - 28.24gn h&n barracuda hunter extreme at 925 fps.
And have you had issues with broken belleville washers( only the black ones)?
If you are willing to give up the safety of the burst disc then yes a pressure indicator could be installed in the low pressure burst disc location.
Something to consider. If the air rifle you are using has been properly certified it would have had to undergo the 5/3 testing pressure. So an airgun that operates at 1100 PSI like the .177 Gauntlet for instance, will need to pass a 1833 PSI test. Now this maximum pressure test should not be confused with operational pressure which was established as 1100 PSI in this case. If the regulator would to fail for some reason, the low side burst disc is the only thing stopping that airgun from being exposed to 4500 PSI.
In the case of the .25 Gauntlet, its operating pressure is 1900 PSI which means it could safely see 3150 PSI and not fail. Again seeing the 3150 PSI and not failing does not mean it should operate at that pressure.
There are Belleville washer calculators that will allow you to determine what the range of a stack would be but typically they are premium applications that require some sort of buy in.
Another thing to do is read through some of the previous post here on the GTA which will walk you through the paths already walked.
Examples:
https://www.gatewaytoairguns.org/GTA/index.php?topic=49648.20 (https://www.gatewaytoairguns.org/GTA/index.php?topic=49648.20)
https://www.gatewaytoairguns.org/GTA/index.php?topic=137971.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=137971.0)
As for broken belleville washers, I have seen them loose tension or flatten but not break.
Be safe