Tuning HM1000x RAW making sense of shot string.

[corny]

The rifle has a peek poppet and reg seat, otherwise stock. The reg is set at 130 with best fittings tester (I suspect the gauge may be low) 

the questions I have, why the constant increase in velocity?
How am I getting that number of 60fpe shots?

Is this acceptable ES for this rifle? 


Created: 11/10/21 05:31 PM

Description: hm1000x

Notes 1: peek poppet 

Notes 2: 130bar reg

Distance to Chrono(FT): 1.00

Ballistic Coefficient: 62.000

Bullet Weight(gr): 34.00

Temp: 66 °F

BP: 1024.00 inHg

Altitude: 0.00

# FPS FT-LBS

74 897 60.75 30.50

73 ERROR 2

72 ERROR 2

71 ERROR 2

70 ERROR 2

69 ERROR 2

68 907 62.12 30.84

67 ERROR 2

66 ERROR 2

65 917 63.49 31.18

64 ERROR 2

63 ERROR 2

62 921 64.05 31.31

61 ERROR 2

60 918 63.63 31.21

59 917 63.49 31.18

58 914 63.08 31.08

57 922 64.19 31.35

56 915 63.22 31.11

55 ERROR 2

54 916 63.36 31.14

53 914 63.08 31.08

52 912 62.80 31.01

51 916 63.36 31.14

50 910 62.53 30.94

49 914 63.08 31.08

48 915 63.22 31.11

47 905 61.84 30.77

46 914 63.08 31.08

45 910 62.53 30.94

44 917 63.49 31.18

43 918 63.63 31.21

42 914 63.08 31.08

41 906 61.98 30.80

40 911 62.67 30.97

39 900 61.16 30.60

38 907 62.12 30.84

37 904 61.71 30.74

36 912 62.80 31.01

35 906 61.98 30.80

34 909 62.39 30.91

33 910 62.53 30.94

32 906 61.98 30.80

31 903 61.57 30.70

30 904 61.71 30.74

29 900 61.16 30.60

28 900 61.16 30.60

27 903 61.57 30.70

26 896 60.62 30.46

25 893 60.21 30.36

24 902 61.43 30.67

23 894 60.35 30.40

22 890 59.81 30.26

21 897 60.75 30.50

20 895 60.48 30.43

19 898 60.89 30.53

18 897 60.75 30.50

17 899 61.03 30.57

16 894 60.35 30.40

15 893 60.21 30.36

14 892 60.08 30.33

13 900 61.16 30.60

12 892 60.08 30.33

11 896 60.62 30.46

10 896 60.62 30.46

9 894 60.35 30.40

8 889 59.68 30.23

7 889 59.68 30.23

6 896 60.62 30.46

5 ERROR 2

4 ERROR 2

3 898 60.89 30.53

2 894 60.35 30.40

1 905 61.84 30.77

Average: 904.5 FPS

SD: 9.2 FPS

Min: 889 FPS

Max: 922 FPS

Spread: 33 FPS

Shot/sec: 0.2

True MV: 904 FPS

Group Size (in): 0.00

 

[elh0102]

Jon, I can't answer your question. My RAW is a standard power HM 1000, but the ES is typically 10-12 fps. I probably missed an earlier post, but what was the reason for replacing the parts mentioned?

 

[corny]

My reg had a bad seal.

the poppet I simply did to lighten the hammer. 

 

[nervoustrig]

I graphed it to help interpret it:

[/url][/img]

It looks to me that it is a result of the input regulation (output pressure falls as reservoir pressure falls) combined with insufficient hammer strike.

In other words, the beginning of the string is slower because the system is operating at a state of partial valve lock. Just ever so slightly. The hammer can't fully overcome the elevated pressure holding the valve closed. Then as the pressure falls, the hammer can more fully knock open the valve, increasing lift and dwell, causing the velocity to rise.

How did you go about setting the hammer spring tension?

 

[Lewis]

^^ Bingo ^^

The way to verify this is to reduce your reg pressure just a bit. If less reg pressure results in an increase in speed, you have partial valve lock. Similarly, increasing the reg pressure would result in decreased speed.

 

[mubhaur]

I don't understand why there can be a valve lock. ES is not bad but not good either.

Looks like the regulator doesn't give consistent pressure. 

Hammer lube can play a part in inconsistency too.

Further if there is some minor issue with the reg, the hammer, hammer spring and valve spring should take care of slight flaw of reg.

Complete combination has to be addressed as I see the situation. 

I suggest to start with only replacing the valve spring with a harder one. Then share the results. 

With peek poppet and low reg pressure you may get good shot count but you will not be able to go up to 70 ftlb by just adjusting the HST.

For good shot count alongwith the option of going up in power, normally a bigger plenum is required. 

Bhaur 

 

[corny]

I graphed it to help interpret it:

[/url][/img]

It looks to me that it is a result of the input regulation (output pressure falls as reservoir pressure falls) combined with insufficient hammer strike.

In other words, the beginning of the string is slower because the system is operating at a state of partial valve lock. Just ever so slightly. The hammer can't fully overcome the elevated pressure holding the valve closed. Then as the pressure falls, the hammer can more fully knock open the valve, increasing lift and dwell, causing the velocity to rise.

How did you go about setting the hammer spring tension?

That’s neat…thanks.

HS was set to the full tank pressures. Meaning at 245 bar bottle fill…any slight decrease in HS will result in number around 875-880 which is slower than I’d like to see.

however, I also don’t want to see any speeds over 900. 

i think my reg needs to be re evaluated. 


as can be seen in shot string, rifle is shooting slowest when bottle is between 250-200bar. Almost like the reg is letting a little more air 

 

[corny]

I don't understand why there can be a valve lock. ES is not bad but not good either.

Looks like the regulator doesn't give consistent pressure. 

Hammer lube can play a part in inconsistency too.

Further if there is some minor issue with the reg, the hammer, hammer spring and valve spring should take care of slight flaw of reg.

Complete combination has to be addressed as I see the situation. 

I suggest to start with only replacing the valve spring with a harder one. Then share the results. 

With peek poppet and low reg pressure you may get good shot count but you will not be able to go up to 70 ftlb by just adjusting the HST.

For good shot count alongwith the option of going up in power, normally a bigger plenum is required. 

Bhaur

Stronger HS or just increase HS tension? 
right now it’s backed out all the way.

 

[mubhaur]

I don't understand why there can be a valve lock. ES is not bad but not good either.

Looks like the regulator doesn't give consistent pressure. 

Hammer lube can play a part in inconsistency too.

Further if there is some minor issue with the reg, the hammer, hammer spring and valve spring should take care of slight flaw of reg.

Complete combination has to be addressed as I see the situation. 

I suggest to start with only replacing the valve spring with a harder one. Then share the results. 

With peek poppet and low reg pressure you may get good shot count but you will not be able to go up to 70 ftlb by just adjusting the HST.

For good shot count alongwith the option of going up in power, normally a bigger plenum is required. 

Bhaur

Stronger HS or just increase HS tension? 
right now it’s backed out all the way.

Install a stronger valve return spring 

 

[elh0102]

The only time I had a velocity consistency issue with my RAW, at Martin's suggestion I cleaned and lubed the the hammer assembly, and that fixed it. You mentioned that your HST is at full out, or light. I've never had a rifle that gave its best results at either extreme of the adjustment range. But I've never used any modified parts either.

 

[biohazardman]

I agree with some others. Looks to me like a slight increase on the hammer spring would take care of that. Decreasing the reg pressure the tiny amount needed will be a bit more difficult but would werq as well.

 

[corny]

The only time I had a velocity consistency issue with my RAW, at Martin's suggestion I cleaned and lubed the the hammer assembly, and that fixed it. You mentioned that your HST is at full out, or light. I've never had a rifle that gave its best results at either extreme of the adjustment range. But I've never used any modified parts either.

Martin serviced the rifles less that 3 weeks ago. 
I did have the hammer spring out, has a very light lubricant on it. Didn’t pull the hammer. 

 

[corny]

I don't understand why there can be a valve lock. ES is not bad but not good either.

Looks like the regulator doesn't give consistent pressure. 

Hammer lube can play a part in inconsistency too.

Further if there is some minor issue with the reg, the hammer, hammer spring and valve spring should take care of slight flaw of reg.

Complete combination has to be addressed as I see the situation. 

I suggest to start with only replacing the valve spring with a harder one. Then share the results. 

With peek poppet and low reg pressure you may get good shot count but you will not be able to go up to 70 ftlb by just adjusting the HST.

For good shot count alongwith the option of going up in power, normally a bigger plenum is required. 

Bhaur

Stronger HS or just increase HS tension? 
right now it’s backed out all the way.

Install a stronger valve return spring

Interesting idea…but wouldn’t that in affect make the valve harder to open? I can see how that would help on the majority of the shots. However…wouldn’t it make the top portion of the shot string worse? 

 

[corny]

I agree with some others. Looks to me like a slight increase on the hammer spring would take care of that. Decreasing the reg pressure the tiny amount needed will be a bit more difficult but would werq as well.

Possibly, but I’d rather not have the rifles shoot that hot. 
I want steady 890-900

 

[elh0102]

I agree with some others. Looks to me like a slight increase on the hammer spring would take care of that. Decreasing the reg pressure the tiny amount needed will be a bit more difficult but would werq as well.

Possibly, but I’d rather not have the rifles shoot that hot. 
I want steady 890-900

How did it shoot as delivered? Sounds like you might be looking for a tune that is below the general HP range. 

 

[mubhaur]

I agree with some others. Looks to me like a slight increase on the hammer spring would take care of that. Decreasing the reg pressure the tiny amount needed will be a bit more difficult but would werq as well.

Possibly, but I’d rather not have the rifles shoot that hot. 
I want steady 890-900

With the heavier valve spring, I you don't get required fps even after increasing HST, put a bit heavier hammer spring too.

 

[mubhaur]

If you gave 60 ftlb version you should set the reg pressure around 145 bars. Then test for consistency. 

If you don't get consistency then put heavier valve return spring. 

If fps drops, install a bit heavier hammer spring or put spacers under the hammer spring to increase the tension a bit.

 

[nervoustrig]

A heavier valve spring may improve the ES in a general way but it will not correct the rising trend.

Since your goal is to keep the velocity under 900fps, you will want to reduce the regulator’s setpoint. Then manipulate the hammer spring tension to find the maximum velocity (max for this new pressure). Finally, back off the hammer spring tension until the velocity falls to 95 – 97% of the max. At this state of tune, it will be less sensitive to minor pressure variations…be they regulator linearity, creep, temperature change, or whatever.

 

[corny]

If you gave 60 ftlb version you should set the reg pressure around 145 bars. Then test for consistency. 

If you don't get consistency then put heavier valve return spring. 

If fps drops, install a bit heavier hammer spring or put spacers under the hammer spring to increase the tension a bit.

Sorry I didn’t mention that.

this is the hm1000x in 25 cal

yes. 60fpe

 

[corny]

Yes I agree, I need to figure out what my reg is doing. I don’t think my tester gauge is working properly. 



once I have that worked out. 

I can do what mubhaur is suggesting in the springs