• Jefferson State Airrifles
  • Air Gun Web - Expert Airgun Reviews
  • Hajimoto Productions
  • Airgun Angie - Backyard Shooting
  • Nielsen Specialty Ammo
  • Dynamic Air Rifles
  • FX Airguns
  • DonnyFL - When silence is a priority
  • Airgun Archery Fun
  • Pyramyd Air
  • Saber Tactical
  • New England Airgun
  • Umarex Airguns
  • Contact us
  • Utah Airguns
  • SEKHMET Airgun Accessories
  • Freedom Gun Targets
  • Evanix Airguns at Airgun Pro Shop
Jefferson State Airrifles
Air Gun Web - Expert Airgun Reviews
Hajimoto Productions
Airgun Angie - Backyard Shooting
Nielsen Specialty Ammo
Dynamic Air Rifles
FX Airguns
DonnyFL - When silence is a priority
Airgun Archery Fun
Pyramyd Air
Saber Tactical
New England Airgun
Umarex Airguns
Contact us
Utah Airguns
SEKHMET Airgun Accessories
Freedom Gun Targets
Evanix Airguns at Airgun Pro Shop


Author Topic: Hajimoto ???  (Read 1377 times))

Offline scion19801

  • Expert
  • *****
  • Posts: 1051
  • yes
  • Real Name: Dan
Hajimoto ???
« on: March 22, 2020, 12:23:05 PM »
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
  • USA, NY, Ithaca
Umarex Gauntlet .25, Hawke vantage 3-12x44 sf, jsar super tune kit, adjustable flex regulator, .38l bottle, rocker1 LDC

Airforce Condor .25 cal, Custom LDC. .145" tophat, power wheel 10, 24-2500 psi fills. 3d printed bipod adapter. Nikko mountmaster 3-12x50AO

FX Impact MK2 700mm .25 cal, element helix 6-24x50, slug kit, both superior liners, slug A liner, carbon fiber barrel liners. .22 stx original pellet liner and slug A liner in 700 mm.

3d printing services as well. just send me an PM

Offline Hajimoto

  • Tweak Geek Shooter'er
  • Moderator
  • Expert
  • *****
  • Posts: 1432
  • yes
  • Real Name: Haji
Re: Hajimoto ???
« Reply #1 on: March 22, 2020, 12:52:55 PM »
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
  • Western Massachusetts, USA

Offline scion19801

  • Expert
  • *****
  • Posts: 1051
  • yes
  • Real Name: Dan
Re: Hajimoto ???
« Reply #2 on: March 22, 2020, 01:56:09 PM »
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?
  • USA, NY, Ithaca
Umarex Gauntlet .25, Hawke vantage 3-12x44 sf, jsar super tune kit, adjustable flex regulator, .38l bottle, rocker1 LDC

Airforce Condor .25 cal, Custom LDC. .145" tophat, power wheel 10, 24-2500 psi fills. 3d printed bipod adapter. Nikko mountmaster 3-12x50AO

FX Impact MK2 700mm .25 cal, element helix 6-24x50, slug kit, both superior liners, slug A liner, carbon fiber barrel liners. .22 stx original pellet liner and slug A liner in 700 mm.

3d printing services as well. just send me an PM

Offline Hajimoto

  • Tweak Geek Shooter'er
  • Moderator
  • Expert
  • *****
  • Posts: 1432
  • yes
  • Real Name: Haji
Re: Hajimoto ???
« Reply #3 on: March 22, 2020, 02:07:21 PM »
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.




Hajimoto
  • Western Massachusetts, USA

Offline scion19801

  • Expert
  • *****
  • Posts: 1051
  • yes
  • Real Name: Dan
Re: Hajimoto ???
« Reply #4 on: March 22, 2020, 02:16:45 PM »
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.
« Last Edit: March 22, 2020, 02:19:24 PM by scion19801 »
  • USA, NY, Ithaca
Umarex Gauntlet .25, Hawke vantage 3-12x44 sf, jsar super tune kit, adjustable flex regulator, .38l bottle, rocker1 LDC

Airforce Condor .25 cal, Custom LDC. .145" tophat, power wheel 10, 24-2500 psi fills. 3d printed bipod adapter. Nikko mountmaster 3-12x50AO

FX Impact MK2 700mm .25 cal, element helix 6-24x50, slug kit, both superior liners, slug A liner, carbon fiber barrel liners. .22 stx original pellet liner and slug A liner in 700 mm.

3d printing services as well. just send me an PM

Offline Hajimoto

  • Tweak Geek Shooter'er
  • Moderator
  • Expert
  • *****
  • Posts: 1432
  • yes
  • Real Name: Haji
Re: Hajimoto ???
« Reply #5 on: March 22, 2020, 06:22:39 PM »
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.

  • Western Massachusetts, USA

Offline scion19801

  • Expert
  • *****
  • Posts: 1051
  • yes
  • Real Name: Dan
Re: Hajimoto ???
« Reply #6 on: March 22, 2020, 06:39:49 PM »
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
  • USA, NY, Ithaca
Umarex Gauntlet .25, Hawke vantage 3-12x44 sf, jsar super tune kit, adjustable flex regulator, .38l bottle, rocker1 LDC

Airforce Condor .25 cal, Custom LDC. .145" tophat, power wheel 10, 24-2500 psi fills. 3d printed bipod adapter. Nikko mountmaster 3-12x50AO

FX Impact MK2 700mm .25 cal, element helix 6-24x50, slug kit, both superior liners, slug A liner, carbon fiber barrel liners. .22 stx original pellet liner and slug A liner in 700 mm.

3d printing services as well. just send me an PM

Offline scion19801

  • Expert
  • *****
  • Posts: 1051
  • yes
  • Real Name: Dan
Re: Hajimoto ???
« Reply #7 on: April 17, 2020, 04:41:40 PM »
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.
  • USA, NY, Ithaca
Umarex Gauntlet .25, Hawke vantage 3-12x44 sf, jsar super tune kit, adjustable flex regulator, .38l bottle, rocker1 LDC

Airforce Condor .25 cal, Custom LDC. .145" tophat, power wheel 10, 24-2500 psi fills. 3d printed bipod adapter. Nikko mountmaster 3-12x50AO

FX Impact MK2 700mm .25 cal, element helix 6-24x50, slug kit, both superior liners, slug A liner, carbon fiber barrel liners. .22 stx original pellet liner and slug A liner in 700 mm.

3d printing services as well. just send me an PM

Offline Backyard Bandit

  • Shooter
  • *
  • Posts: 3
  • yes
  • Real Name: Robert
Re: Hajimoto ???
« Reply #8 on: September 01, 2020, 10:22:44 AM »
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)?
  • USA, GA, Martinez

Offline scion19801

  • Expert
  • *****
  • Posts: 1051
  • yes
  • Real Name: Dan
Re: Hajimoto ???
« Reply #9 on: September 01, 2020, 01:16:04 PM »
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.
  • USA, NY, Ithaca
Umarex Gauntlet .25, Hawke vantage 3-12x44 sf, jsar super tune kit, adjustable flex regulator, .38l bottle, rocker1 LDC

Airforce Condor .25 cal, Custom LDC. .145" tophat, power wheel 10, 24-2500 psi fills. 3d printed bipod adapter. Nikko mountmaster 3-12x50AO

FX Impact MK2 700mm .25 cal, element helix 6-24x50, slug kit, both superior liners, slug A liner, carbon fiber barrel liners. .22 stx original pellet liner and slug A liner in 700 mm.

3d printing services as well. just send me an PM

Offline Hajimoto

  • Tweak Geek Shooter'er
  • Moderator
  • Expert
  • *****
  • Posts: 1432
  • yes
  • Real Name: Haji
Re: Hajimoto ???
« Reply #10 on: September 02, 2020, 04:38:32 AM »
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=137971.0

As for broken belleville washers, I have seen them loose tension or flatten but not break.


Be safe

  • Western Massachusetts, USA