Tuning HM1000x RAW making sense of shot string.

[corny]

So…after farther testing with the reg tester. 
the regulator pressure is definitely rising with the bottle pressure. while I don’t trust my gauge for a set point, the rise in pressure seems to be about 6-8bar from 130 to 250 on the bottle. 
I don’t know why my reg seat showing so much damage already, but I tried to polish it with 6000 knife stones and leather strops. I’ll see if it settle down now.



im starting to wondering if the opposite brass part isn’t damaging my seals. 

 

[nervoustrig]

Excellent picture of the seal at the end of the piston. 

Yes, the indention is prima facie evidence of why the regulator’s output is sensitive to the reservoir pressure rising and falling. Additionally, the overlapping ring at the 11 o’clock to 2 o’clock positions may be a key contributor to the severity of it.

I agree about inspecting the orifice that it mates against. Carefully polish its surface so it won’t wear the plastic seal so badly, then go ahead and dress the end of the piston until the ring(s) are completely gone.

 

[corny]

So..question what the best way to get the brass piece out of the bottom of the reg.

second question, I’m guessing I have already removed a thou or so from the nose of the seal. How much can I still take off before I press in a new piece of peek? 


as in theory, this lengthens the stroke of the reg? 

 

[corny]

Excellent picture of the seal at the end of the piston. 

Yes, the indention is prima facie evidence of why the regulator’s output is sensitive to the reservoir pressure rising and falling. Additionally, the overlapping ring at the 11 o’clock to 2 o’clock positions may be a key contributor to the severity of it.

I agree about inspecting the orifice that it mates against. Carefully polish its surface so it won’t wear the plastic seal so badly, then go ahead and dress the end of the piston until the ring(s) are completely gone.

It’s not really a lip, raw inserts delrin, and must use some kind of a crimping machine to crimp the nose of that piston. Keeping the delrin in place. 
u can clearly see a 3 point crimp mark. And the hole has three lobes indented 

they use a simular process on the valve poppet seat, crimping the pin, so the popped has a little friction sliding onto the pin. And stays in place.

 

[nervoustrig]

For the first option—sanding down the OEM seal until you get a fresh flat surface—yes that will increase the piston travel by a few thousandths which will shift the setpoint up by some amount. I don’t know if your regulator has a moveable seat for adjusting the setpoint but if it does, that’s how you would compensate. Otherwise what you would do is take out a comparable amount of shim stock from the Belleville stack…or flat sand the concave side of all the washers just a smidge. Given we have already established you need to reduce the setpoint a little to keep it below 900fps, you were going to need to tinker with the setpoint anyway. 

Regarding the second option—replacing the seal—the crimp feature is massive overkill. A simple round pocket works just fine. I just size the seal on the lathe for a couple of thousandths interference fit and press it in. It’s not going anywhere…there are no forces acting on it to push it out.

But of course the first challenge is getting the old one out. I would chuck it up in the lathe and peck at it with a drill bit until the tip just breaks through the bottom of the seal. Then use a pick to dig out the remnants. Then grind a HSS cutter to bore out the ID…use light cuts to remove the tri-lobe feature so it will accept a simple cylindrical replacement.

 

[SpiralGroove]

Hey Jon,

I thought you'd changed out the regulator seat from Delrin to Peek - Right?

I think I've used a 1/8" drill bit to bore out my seats, if not the next size up of 9/64".

+1 - "Regarding the second option—replacing the seal—the crimp feature is massive overkill. A simple round pocket works just fine. I just size the seal on the lathe for a couple of thousandths interference fit and press it in. It’s not going anywhere…there are no forces acting on it to push it out."

 

[corny]

So I have now replaced the seat twice. With peek.


polished both the seal and the brass inlet piece.

also replaced the small oring.

im still gaining 100psi or 6.9 bar on the reg when the bottle pressure goes from 150 to 250 bar. 
and it maintains that setpoint till it come back down to 200 bar 

photo show 150 versus 240 bottle pressure 

 

[corny]

Basicly the reg setpoint from a 250 bar fill will slowly drop 6-7bar or 100psi bar till the bottle hits 150 bar 

now I’m not sure if that’s what can be expected from a regulator. I’ll be honest, I’ve never analyzed one to this depth before. 
but I don’t see how I can tune my hammer to that kind of a pressure decrease. And I think my shot string tells the story 

 

[corny]

This is the piston now…

 

[corny]

How much free stroke should the reg have? 

 

[nervoustrig]

the reg setpoint from a 250 bar fill will slowly drop 6-7bar or 100psi bar till the bottle hits 150 bar 

....I don’t see how I can tune my hammer to that kind of a pressure decrease. And I think my shot string tells the story

A pressure change of 100psi is not a big deal.

A well tuned unregulated PCP maintains a stable velocity over a pressure range spanning several hundred PSI. So will a regulated gun. For a small change of just 100psi, simply getting the hammer strike set to the knee will fix it right up.

 

[corny]

So…after spending considerable time on my leather strops with the piston head. I seem to be getting far better results. Reg refresh seem slower on the lower end of the spectrum, but it’s coming back really nice. 


I spent the last hour figuring out max power slowly tuning down the plenum. I settled on 124-127 bar as the max power at that reg setting is 924fps. With king heavies. Then I backed out the HS till I hit the 890 900

range. To me this makes Sence, but what I don’t get is why common knowledge on this rifle is a 145-150 reg pressure? 

 

[mubhaur]

So…after spending considerable time on my leather strops with the piston head. I seem to be getting far better results. Reg refresh seem slower on the lower end of the spectrum, but it’s coming back really nice. 


I spent the last hour figuring out max power slowly tuning down the plenum. I settled on 124-127 bar as the max power at that reg setting is 924fps. With king heavies. Then I backed out the HS till I hit the 890 900

range. To me this makes Sence, but what I don’t get is why common knowledge on this rifle is a 145-150 reg pressure? 

I personally prefer around 145 bars on reg on this gun. The reason being that I have multiple barrels for this gun. In various conditions various barrels work best.

To me in windy conditions the BSA barrel works great but it shoots great at 960 fps.

Sometimes I want to try slugs at high power.

So considering multiple scenarios I keep the reg at 145 bars to achieve the required fps with various projectiles. 

If I have to restrict myself to one barrel and one amo at a certain fps, you have done the right method of tuning.

Bhaur

 

[corny]

So…after spending considerable time on my leather strops with the piston head. I seem to be getting far better results. Reg refresh seem slower on the lower end of the spectrum, but it’s coming back really nice. 


I spent the last hour figuring out max power slowly tuning down the plenum. I settled on 124-127 bar as the max power at that reg setting is 924fps. With king heavies. Then I backed out the HS till I hit the 890 900

range. To me this makes Sence, but what I don’t get is why common knowledge on this rifle is a 145-150 reg pressure? 

I personally prefer around 145 bars on reg on this gun. The reason being that I have multiple barrels for this gun. In various conditions various barrels work best.

To me in windy conditions the BSA barrel works great but it shoots great at 960 fps.

Sometimes I want to try slugs at high power.

So considering multiple scenarios I keep the reg at 145 bars to achieve the required fps with various projectiles. 

If I have to restrict myself to one barrel and one amo at a certain fps, you have done the right method of tuning.

Bhaur

As of right now, I have only one barrel. 
so yes, I tune to one ammo. I might try stronger valve return spring now. 

 

[Feinwerk]

Be mindful of the type of lubrication you use on your hammer. You do not want to use a grease or oil with varying viscosity and friction levels fluctuating with temperature/viscosity effects. For the best consistency, I would think that you might want to try burnishing the sliding surfaces with a swab and graphite powdered lubricant for the most consistent friction. This is readily available in stores sold in a tiny tube for lubricating locks.

Good luck!

 

[elh0102]

I lube the hammer with a light coat of Mobile One motor oil, upon the recommendation of the maker. I'm sure it is a multi-viscosity oil, but I've never experienced any variance in performance. I suppose if you shot over huge range of temps, it might be an issue. But frankly, that kind of extreme temp variation will have an effect on everything in the rifle, so I don't fret about it. 

 

[corny]

And here I have the new shot string with reg working…pretty happy with the result. 6 mags…



Created: 11/13/21 02:59 PM
Description: hm1000x .25cal
Notes 1: 124-127bar reg
Notes 2: peep poppet and reg seat 
Distance to Chrono(FT): 3.00
Ballistic Coefficient: 0.062
Bullet Weight(gr): 33.95
Temp: 72 °F
BP: 1020.00 inHg
Altitude: 0.00
# FPS FT-LBS PF
74 883 58.79 29.98
73 880 58.39 29.88
72 889 59.59 30.18
71 900 61.07 30.56
70 895 60.40 30.39
69 895 60.40 30.39
68 ERROR 2
67 900 61.07 30.56
66 892 59.99 30.28
65 895 60.40 30.39
64 904 61.62 30.69
63 894 60.26 30.35
62 898 60.80 30.49
61 ERROR 2
60 ERROR 2
59 890 59.72 30.22
58 900 61.07 30.56
57 898 60.80 30.49
56 899 60.94 30.52
55 895 60.40 30.39
54 900 61.07 30.56
53 892 59.99 30.28
52 894 60.26 30.35
51 897 60.67 30.45
50 880 58.39 29.88
49 900 61.07 30.56
48 899 60.94 30.52
47 891 59.86 30.25
46 899 60.94 30.52
45 907 62.03 30.79
44 897 60.67 30.45
43 893 60.13 30.32
42 897 60.67 30.45
41 901 61.21 30.59
40 897 60.67 30.45
39 896 60.53 30.42
38 898 60.80 30.49
37 885 59.05 30.05
36 893 60.13 30.32
35 ERROR 2
34 892 59.99 30.28
33 898 60.80 30.49
32 888 59.45 30.15
31 897 60.67 30.45
30 892 59.99 30.28
29 894 60.26 30.35
28 886 59.19 30.08
27 895 60.40 30.39
26 887 59.32 30.11
25 888 59.45 30.15
24 ERROR 2
23 890 59.72 30.22
22 898 60.80 30.49
21 894 60.26 30.35
20 893 60.13 30.32
19 887 59.32 30.11
18 896 60.53 30.42
17 891 59.86 30.25
16 894 60.26 30.35
15 ERROR 2
14 881 58.52 29.91
13 887 59.32 30.11
12 885 59.05 30.05
11 900 61.07 30.56
10 896 60.53 30.42
9 891 59.86 30.25
8 881 58.52 29.91
7 888 59.45 30.15
6 889 59.59 30.18
5 897 60.67 30.45
4 893 60.13 30.32
3 882 58.65 29.94
2 892 59.99 30.28
1 888 59.45 30.15
Average: 893.1 FPS
SD: 5.9 FPS
Min: 880 FPS
Max: 907 FPS
Spread: 27 FPS
Shot/sec: 0.1
True MV: 897 FPS
Group Size (in): 0.00

 

[SpiralGroove]

Jon,

What adjustments, if any did U make?

 

[corny]

I polished the reg seat with leather strops. 
black, green, blue stropping compound. I use them for knife sharpening. This fixed my reg issues. 

then I fine tuned the reg till the set point was 924fps at max power. For my gun that right around 124-127 bar 

backed off the HS till it reached 890-900 fps.

All springs are still oem. Only mods the gun has it peep poppet and reg seat. 

I’m still surprised at the shot count it nearly doubled

that one 907fps shot increased the ES by 6 

 

[SpiralGroove]

Yeah Jon,

I'd be happy for now! 

Maybe re-test in a month to see if regulator has smoothed out a little.

ES could likely be reduced a little more by regulator set-point, valve spring, hammer weight tweaks or hammer spring tweaks, but maybe not worth the hassle. 

Shooter errors more likely the cause of missed-shots .... like my situation.