Author Topic: A new HUMA's in the house  (Read 1018 times)

mcoulter

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Re: A new HUMA's in the house
« Reply #15 on: May 07, 2018, 06:19:05 PM »
Just a quick update regarding the HUMA regulator. 

The installation instructions were originally less than clear regarding the small m3 allen screw that goes into the brass pressure adjusting set screw.  The instructions have since been updated to confirm that in the Royale, this m3 should not be left on the regulator.  Other FX rifles may need this m3 left on the reg during the intallation, but NOT the Royale... 

This screw should just be screwed in when you need to remove the reg.  It makes it easy to pluck the reg out of the body, but need to be removed afterwards:



If left in, this m3 allen will engage with the tube receiver when that part is screwed into the block.  This is what will happen if its left in...  it will engage with the screw and actuate the regulator's pressure.  This is the stem from the regulator:



I am starting from scratch by screwing the set screw into the regulator and then backing it out a couple of turns and testing velocities.  With two turns out on the regulator's set screw and two turn out on the hammer spring, I got the short string below with JSB 18s.  Obviously I'm not where I need to be with the pressure so I will continue to back it out one turn at a time until the rifle is back in normal range (120 to 140 BAR).

The 1st 4 shots of the magazine did not register but the next ones did and were pretty consistent.

466 fps
467 fps
467 fps
466 fps
468 fps
466 fps
468 fps
472 fps

That's all for now!
« Last Edit: May 07, 2018, 06:24:56 PM by mcoulter »
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Alan

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Re: A new HUMA's in the house
« Reply #16 on: May 08, 2018, 05:50:19 AM »
As you're no doubt aware, juxtaposing the pressure with the hammer preload is a tedious job at best.

I recently did that exercise with a new hammer and regulator rebuild for my .25 caliber Cobra. I think I shot about 150 rounds, but I did have a starting point obviously. During the process I did discover another issue—the hammer retaining screw was a bit too long for the new hammer, resulting is some inconstancies during testing due to spring interference. Once that was fixed, everything settled down to a very consistent 868 FPS with 25.39 grainers, at a regulated 1,850 PSI.

I trust you won't have to go through THAT whole process.
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Alan

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mcoulter

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Re: A new HUMA's in the house
« Reply #17 on: May 09, 2018, 09:58:54 AM »
Yup, a bit tedious but still enjoyable trigger time  :-)

These numbers are from short (12-shot) strings with the hammer spring at 3 turns out.  I get 6-full turns of adjustment from the hammer spring, so I figured starting in the middle is as good of a place as any. 

The turn reference below are counter-clockwise turns OUT on the regulator after screwing the regulator's set screw all the way in.  As you turn counter-clockwise, the regulator pressure increases.

2.0 turns = 690 fps
2.5 turns = 885 fps
2.75 turns = 915 fps
3.0 turns = 935 fps

Looking at the set screw scale these are the pressures noted at these turns out.  (For my future reference; when turned all the way in, the marker on the set screw points to 140.)

2.50 turns = 100 bar
2.75 turns = 120 bar

Nex I will:

1) Set the reg at 110 bar (2.6-ish turns out)

2) Do more hammer spring testing to check velocities on each turn on the tensioner.

3) Shoot a full string from my 220 bar fill down to check for consistency and to see where it drops off the regulator now.
« Last Edit: May 09, 2018, 10:03:12 AM by mcoulter »
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mcoulter

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Re: A new HUMA's in the house
« Reply #18 on: May 14, 2018, 11:53:30 AM »
OK, I have determined a few things:

1) The m3 screw definitely is NOT needed in my model FX (confirmed with huma)

2) When increasing the regulator pressure by adjusting the regulator set screw counter-clockwise, you have to turn past the desired pressure and then back clockwise to your desired pressure.  Otherwise, the screw may not remain at the desired pressure.  I  installed it at the marked 120 bar setting and it came out at the 135 bar setting.  (I don't recall if I followed this procedure or not in the long string below.)

3) My regulator's scale tape seem to be off by quite a bit now.  I have to assume this is because of my "fiddling" with it.  As mentioned above, my regulator came out showing 135 bar, but the velocity starts dropping around 170 bar (50 shots) and the regulator starts making a noise around 160 bar (63 shots).  On some FX models this sound corresponds to the pressure being below the regulator adjustment. 

I am going to assume that the actual regulator set pressure is 20 to 30 bar ABOVE what the tape indicates.   So if I set the reg at 100 bar, it may be more like 120 to 130 bar.



Here's the data:
http://bit.ly/2vWA7u8 (Tab = 5/12/18 135B 3HS)

Here's the graph:




I lowered the regulator one more time to the 100 bar mark (2.5 turns out) and did another hammer spring test:






HS    FPS
0   839
1   850
2   862
3   866
4   863
5   847
6   812
7   754
8   690


Before I do any more shooting I will remove and examine the regulator to see if the set screw is still in the same position.  As tedious as this sounds, its actually not hard to do at all.  If I actually had one afternoon to play, I am sure I do all the testing I would need to do!  Unfortunately my trigger time is limited so each test might take me a week or so to get to!

 :(
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rsterne

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Re: A new HUMA's in the house
« Reply #19 on: May 19, 2018, 09:27:35 AM »
Depending on your needs, 5-6 turns out would be the velocity range I would tune to at that pressure....

Bob
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