tinkering with airguns is fun

[3crows]

Thank you for the detail description and photos. That is a quality post! Great work .

[triggertreat]

Liam, very nice work and write up.  That SSG should work well.  Hopefully the O-rings stay consistent.

Here's my last DIY SSG build just to gander at:  https://www.gatewaytoairguns.org/GTA/index.php?topic=110660.msg1056871#msg1056871

[lm22]

Thank you for the detail description and photos. That is a quality post! Great work .

Thank you!

Liam, very nice work and write up.  That SSG should work well.  Hopefully the O-rings stay consistent.

Here's my last DIY SSG build just to gander at:  https://www.gatewaytoairguns.org/GTA/index.php?topic=110660.msg1056871#msg1056871

I guess time will tell on the orings. If they end up proving to be a problem then I'll have to mess with some things. The one on the center bolt is mainly for sound reduction so can be removed without much issue. The ones on the spring stop and spring adjuster are there to prevent the spring stop and the spring from spinning during adjustments so they're not absolutely necessary, but something would have to be done to stop that from happening.

I remember coming across your write up. It was one of the first posts that I read that got me thinking about Ssgs. Nicely done! Thought about making it but decided I wanted to avoid making the hammer any heavier and keep it separate from the ssg.

[triggertreat]

Yes, I really like what you did to the hammer.

[lm22]

Yes, I really like what you did to the hammer.

Thanks, figured why not give it a try. Seems to be working.

[lm22]

Most recent shot string. Opened up the restrictor on the factory reg 3/4s of a turn and added another 1/32nd - 1/16th or so of preload to the ssg to total  about 3/32nds of gap between the hammer and valve with the spring adjuster turned all the way ccw. Made it have more of a traditional bell curve like a unregulated gun but, accuracy depending, I think I might like it.

Pellet: 18.13 grain jsbs
Shots: 120
Avge: 788 fps
Es: 43 fps
Sd: 11
1: 782 - 24.58 fpe
2: ----
3: 779 - 24.39 fpe
4: 778 - 24.32 fpe
5: 780 - 24.45 fpe
6: 779 - 24.39 fpe
7: 783 - 24.64 fpe
8: 779 - 24.39 fpe
9: 777 - 24.26 fpe
10: 777 - 24.26 fpe
11: 772 - 23.95 fpe
12: 783 - 24.64 fpe
13: 777 - 24.26 fpe
14: 772 - 23.95 fpe
15: 778 - 24.32 fpe
16: 772 - 23.95 fpe
17: 776 - 24.20 fpe
18: 779 - 24.39 fpe
19: 776 - 24.20 fpe
20: ----
21: 778 - 24.32 fpe
22: 779 - 24.39 fpe
23: 775 - 24.14 fpe
24: 775 - 24.14 fpe
25: 776 - 24.20 fpe
26: 778 - 24.32 fpe
27: 768 -  23.70 fpe
28: 779 - 24.39 fpe
29: 774 - 24.08 fpe
30: ----
31: 783 - 24.64 fpe
32: 781 - 24.51 fpe
33: 780 - 24.45 fpe
34: 782 - 24.58 fpe
35: 782 - 24.58 fpe
36: 778 - 24.32 fpe
37: 781 - 24.51 fpe
38: 778 - 24.32 fpe
39: 783 - 24.64 fpe
40: 777 - 24.26 fpe
41: 781 - 24.51 fpe
42: 787 - 24.89 fpe
43: 785 - 24.76 fpe
44: 785 - 24.76 fpe
45: 785 - 24.76 fpe
46: 783 - 24.64 fpe
47: 784 - 24.70 fpe
48: 784 - 24.70 fpe
49: ----
50: 777 - 24.26 fpe
51: 787 - 24.89 fpe
52: 789 - 25.02 fpe
53: 785 - 24.76 fpe
54: 782 - 24.58 fpe
55: 786 - 24.83 fpe
56: 781 - 24.51 fpe
57: 781 - 24.51 fpe
58: ----
59: 791 - 25.14 fpe
60: 786 - 24.83 fpe
61: ----
62: 787 - 24.89 fpe
63: 789 - 25.02 fpe
64: 786 - 24.83 fpe
65: 790 - 25.08 fpe
66: 789 - 25.02 fpe
67: 791 - 25.14 fpe
68: 792 - 25.21 fpe
69: 790 - 25.08 fpe
70: 793 - 25.27 fpe
71: 785 - 24.76 fpe
72: 793 - 25.27fpe
73: 790 - 25.08 fpe
74: 789 - 25.02 fpe
75: 787 - 24.89 fpe
76: 792 - 25.21 fpe
77: 787 - 24.89 fpe
78: 792 - 25.21 fpe
79: 790 - 25.08 fpe
80: 786 - 24.83 fpe
81: 784 - 24.70 fpe
82: 795 - 25.40 fpe
83: 795 - 25.40 fpe
84: 793 - 25.27 fpe
85: 796 - 25.46 fpe
86: 792 - 25.21 fpe
87: 801 - 25.78 fpe
89: 801 - 25.78 fpe
90: 795 - 25.40 fpe
91: 801 - 25.78 fpe
92: 799 - 25.66 fpe
93: 805 - 26.04 fpe
94: 802 - 25.85 fpe
95: 805 - 26.04 fpe
96: 808 - 26.24 fpe
97: 808 - 26.24 fpe
98: 807 - 26.17 fpe
99: 808 - 26.24 fpe
100: 808 - 26.24 fpe
101: 800 - 25.72 fpe
102: 810 - 26.37 fpe
103: 809 - 26.30 fpe
104: 799 - 25.66 fpe
105: 807 - 26.14 fpe
106: 811 - 26.43 fpe
107: 807 - 26.17 fpe
108: 806 - 26.11 fpe
109: 807 - 26.17 fpe
110: 806 - 26.11 fpe
111: 806 - 26.11 fpe
112: 803 - 25.91 fpe
113: 804 - 25.98 fpe
114: 804 - 25.98 fpe
115: 799 - 25.66 fpe
116: 796 - 25.46 fpe
117: 797 - 25.53 fpe
118: 794 - 25.34 fpe
119: 793 - 25.27 fpe
120: 790 - 25.08 fpe

[triggertreat]

That's a lot of shots.  I say take notes of your air pressure along the way.  If you were to start the string around shot 41 or even shot 51 on air pressure for that particular tune you would have even better numbers and still lots of shots.

[lm22]

That's a lot of shots.  I say take notes of your air pressure along the way.  If you were to start the string around shot 41 or even shot 51 on air pressure for that particular tune you would have even better numbers and still lots of shots.

Guess that would mean less hand pumping in order to fill the gun as well.

[HunterWhite]

Less hand pumping? Power in power out. If it takes 2 or 3 pumps per shot, its the same per hundred shots. It's just fewer at a time.


Wow! Is this a bottle gun? ~25 FPE x 120 shots is like 3000 FP from the reservoir.  I thought that the famous 40-40 tune was so good, that's 40x40=1600 foot pounds.
Did I do the math wrong?


Hunter

[lm22]

Less hand pumping? Power in power out. If it takes 2 or 3 pumps per shot, its the same per hundred shots. It's just fewer at a time.


Wow! Is this a bottle gun? ~25 FPE x 120 shots is like 3000 FP from the reservoir.  I thought that the famous 40-40 tune was so good, that's 40x40=1600 foot pounds.
Did I do the math wrong?


Hunter

 Very true. Doesn't change how much I have to pump, just when.

Just a factory 215cc tube. When I started out my goal was an at least 50 shots - 30 fpe tune, so something more in line in with the 40-40 tune. Haven't quite reached my fpe goal but the fact that I've increased shot count every time I increased power keeps impressing me. Was crazy to reach my 6th mag and still be at around 2300-2400 psi from a 3000 fill. Was able to keep shooting down to 1500 psi.

[3crows]

Great work.  .

Let me be sure I understand, this is an unregulated rifle?

Wow!!!!!! Impressive shot string either way.

[lm22]

Great work.  .

Let me be sure I understand, this is an unregulated rifle?

Wow!!!!!! Impressive shot string either way.

No. A factory regulated .22 cal Mrod Field and target.

[HunterWhite]

James, the Field and Target Marauder has 215 cc with the regulator because Benjamin Crosman extended the reservoir 2 inches. So even with the regulator it is still 215 cc.
You are right, that is an impressive shot string.


Hunter

[lm22]

More progress. I decided to go back to the 15.89 gr jsbs and see if I could flatten the shot string. Reduced pre-load on the ssg so the hammer to valve gap is now about 1/16th with the spring adjuster fully ccw.
New shot string:

Pellet: .22 cal 15.89 jsb
Shots: 110
Average velocity: 836 fps
Average fpe: 24.72 fpe
ES: 18
SD: 4

1: 835 - 24.61 fpe      2: 838 - 24.79 fpe
3: 835 - 24.61 fpe      4: 838 - 24.79 fpe
5: 834 - 24.55 fpe      6: 831 - 24.38 fpe
7: 833 - 24.50 fpe      8: 837 - 24.73 fpe
9: 832 - 24.44 fpe      10: 833 - 24.50 fpe
11: 837 - 24.73 fpe    12: 835 - 24.61 fpe
13: 832 - 24.44 fpe    14: 835 - 24.61 fpe
15: 828 - 24.20 fpe    16: 836 - 24.67 fpe
17: 835 - 24.61 fpe    18: 836 - 24.67 fpe
19: 827 - 24.14 fpe    20: ----
21: 835 - 24.61 fpe    22: 831 - 24.38 fpe
23: 834 - 24.55 fpe    24: 829 - 24.26 fpe
25: 837 - 24.73 fpe    26: 836 - 24.67 fpe
27: 833 - 24.50 fpe    28: 836 - 24.67 fpe
29: 835 - 24.61 fpe    30: ----
31: 834 - 24.55 fpe    32: 830 - 24.32 fpe
33: 830 - 24.32 fpe    34: 834 - 24.55 fpe
35: 833 - 24.50 fpe    36: 836 - 24.67 fpe
37: 833 - 24.50 fpe    38: ----
39: 839 - 24.85 fpe    40: 839 - 24.85 fpe
41: 832 - 24.44 fpe    42: 836 - 24.69 fpe
43: 837 - 24.73 fpe    44: 834 - 24.55 fpe
45: 843 - 25.09 fpe    46: 836 - 24.67 fpe
47: 835 - 24.61 fpe    48: 833 - 24.50 fpe
49: 833 - 24.50 fpe    50: 837 - 24.73 fpe
51: 833 - 24.50 fpe    52: 837 - 24.73 fpe
53: 832 - 24.44 fpe    54: 841 - 24.97 fpe
55: 840 - 24.91 fpe    56: 839 - 24.85 fpe
57: 837 - 24.73 fpe    58: 839 - 24.85 fpe
59: 844 - 25.15 fpe    60: 843 - 25.09 fpe
61: 842 - 25.03 fpe    62: 842 - 25.03 fpe
63: 843 - 25.09 fpe    64: 837 - 24.73 fpe
65: 840 - 24.91 fpe    66: 844 - 25.15 fpe
67: 843 - 25.09 fpe    68: 832 - 24.44 fpe
69: 836 - 24.67 fpe    70: 844 - 25.15 fpe
71: 836 - 24.67 fpe    72: ----
73: 841 - 24.97 fpe    74: 840 - 24.91 fpe
75: 840 - 24.91 fpe    76: 838 - 24.79 fpe
77: 840 - 24.91 fpe    78: 839 - 24.85 fpe
79: ----                     80: 845 - 25.21 fpe
81: 841 - 24.97 fpe    82: 844 - 25.15 fpe
83: 841 - 24.97 fpe    84: 844 - 25.15 fpe
85: 842 - 25.03 fpe    86: 839 - 24.85 fpe
87: 842 - 25.03 fpe    88: 840 - 24.91 fpe
89: 843 - 25.09 fpe    90: 839 - 24.85 fpe
91: 842 - 25.03 fpe    92: 842 - 25.03 fpe
93: 841 - 24.97 fpe    94: 839 - 24.85 fpe
95: 839 - 24.85 fpe    96: 839 - 24.85 fpe
97: 839 - 24.85 fpe    98: 836 - 24.67 fpe
99: 839 - 24.85 fpe    100: 840 - 24.91 fpe
101: 835 - 24.61 fpe  102: ----
103: 836 - 24.67 fpe  104: 831 - 24.38 fpe
105: 832 - 24.44 fpe  106: 831 - 24.38 fpe
107: 829 - 24.26 fpe  108: ----
109: 832 - 24.44 fpe  110: 829 - 24.26 fpe

[3crows]

James, the Field and Target Marauder has 215 cc with the regulator because Benjamin Crosman extended the reservoir 2 inches. So even with the regulator it is still 215 cc.
You are right, that is an impressive shot string.


Hunter

Ahhh, okay, makes sense now. I did not know the Field Target had a longer tube. That is an amazing string with both pellet grain sizes, longer tube or not!

[HunterWhite]

Yes. Impressive.
That yields 2719 total FPE from 215 cc (13 cu in).


Now where is that efficiency calculator?


Hunter

[eeler1]

Have you noticed changes in the sound level?

[triggertreat]

Yes. Impressive.
That yields 2719 total FPE from 215 cc (13 cu in).


Now where is that efficiency calculator?


Hunter

Would need to know the air pressure start/stop and the plenum volume to calculate the efficiency accurately.  Showing 3% just guessing at psi used.  ES is certainly good.  He's really showing what the FT can really achieve.

[lm22]

Have you noticed changes in the sound level?

Maybe a slight increase in sound but it's barely noticeable if there is.

Yes. Impressive.
That yields 2719 total FPE from 215 cc (13 cu in).


Now where is that efficiency calculator?


Hunter

Using math from Bob Sterne's post in Hard Air Magazine I got right around 1.94 FPE/CI

https://hardairmagazine.com/ham-columns/pcp-efficiency-what-is-it-what-changes-it/

[lm22]

Yes. Impressive.
That yields 2719 total FPE from 215 cc (13 cu in).


Now where is that efficiency calculator?


Hunter

Would need to know the air pressure start/stop and the plenum volume to calculate the efficiency accurately.  Showing 3% just guessing at psi used.  ES is certainly good.  He's really showing what the FT can really achieve.

As far as start/stop pressure it was around 3000 starting and 1500 stopping, not sure what plenum size would be.