AA S200 Bells & Whistles - Poor Results

[Geoff555]

OK spring length. ( new genuine.).
44.35mm.
1.746".
Cheers.
Geoff.

[garym]

Following this with interest. Thanks guys.
I have a similar issue after fitting a Altoros reg to my cz 200.
Altoros advice me to adjust the 'striker spring' to the minimus. I assume they mean the hammer spring.
If I can get 60 shots and a plateau as above I will be very happy.
Cheers G

[rabbitslayer]

Altoros advice me to adjust the 'striker spring' to the minimus. I assume they mean the hammer spring.

Yes, Hammer spring.

[rabbitslayer]

OK spring length. ( new genuine.).
44.35mm.
1.746".
Cheers.
Geoff.

I haven't got my 'verynears' () handy but using a tape measure it looks like it bang on 45mm.

[rabbitslayer]

Isn't decreasing tension on the hammer spring the same as increasing firing valve spring tension? Doesn't it have the same effect?

[garym]

I thought the same, but happy to be enlightened.
Good thread guys.

[Rich]

Not wishing to sound picky, but hammer springs are compression springs not tension springs. You mean reducing the pre-load or increasing it.

The two options aren't quite the same; the striker will have more mass than the firing valve.

[rabbitslayer]

Not wishing to sound picky, but hammer springs are compression springs not tension springs. You mean reducing the pre-load or increasing it.

Thanks for pointing that out Rich.. I take it the firing valve spring also a compression type?

The two options aren't quite the same; the striker will have more mass than the firing valve.

So having more mass means it moves slower than the firing valve is able open / shut? When would you alter the the pre-load on the striker as opposed to the firing valve and what are the differences in effect?

Sorry but genuinely trying to get my head around this..

[rabbitslayer]

Today I had another tinker. I decided to set my sights on the exhaust / firing valve spring. I figured that increasing the pre-load, if nothing else, would shut the gate quicker and help to increase shots per fill. I can't do anymore with the hammer spring (as it is) as it's already fully wound out. I am though collecting four different strength / length springs tomorrow.

Anyway, I emptied the cylinder and started to unscrew the brass end plug which houses the firing valve. I noticed a small amount of resistance. It wasn't hard to turn but didn't feel quite right. I thought back to when I fitted it and remembered that it screwed in freely. All became clear when I came to the end of the thread. There was a little 'pop' and the end plug sprung off quickly followed by the regulator! I'd forgotten that there would still be pressure behind the reg.

This was handy though because I wanted to take another look at the reg setting again but remembered when fitting it, it was quite a tight fit (obviously) and getting the reg body and outer 'o' ring seals past the cylinders internal threads took quite a bit of force. I was worried I'd damage the 'o' rings so I decided not to chance it and forget trying to remove it. So yeah, it came out on it's own. Result.

I turned the reg pressure setting screw in and reduced it to 85 bar (from 95). My logic was that if the reg shut off at a lower pressure then this would also go towards increasing shot count (but could be wrong?). Next I increased preload on the firing valve spring by giving it a 1/8 turn clockwise. I reassembled the cylinder (this time the reg went in a lot easier for some reason), filled it, screwed it back on to the rifle and fired up the chrono.

The chrono results are below but the differences I've noted are:

• The new settings have removed the previous power spike (running off reg) and shot consistency looks a lot flatter with overall max FPS:777/min 766 = 11 (previous settings: 795/780 = 15)

• Although total shot count of 58 doesn't lookalike an improvement (previous: 61), I think it has slightly. Because the cylinder was totally empty, it became quite warm when I filled it and although it indicated 190 bar on the gauge, I think by the time I'd started the test it had cooled down and was more probably only around the 185 bar mark, so I think I'd have easily got another 5 to six full power shot if I'd had noticed before I started.

• Power is down though at just over 11.1 ft/lb from a previous of just under 11.5 ft/lb.

• I still think shots per fill needs to increase considering the standard cylinder is 30ml smaller with reports of over 60 shots per fill (regulated).

Shot FPS Ft/Lb Pressure Check
1 771 11.08 - 185 bar
2 774 11.17
3 771 11.1
4 768 11.02
5 771 11.08 - 180 bar
6 772 11.13
7 768 11.02
8 770 11.06
9 768 11
10 774 11.19
11 771 11.08
12 766 10.95
13 774 11.17
14 772 11.13
15 768 11.02
16 772 11.13 - 160 bar
17 774 11.17
18 773 11.15
19 774 11.19
20 771 11.08
21 771 11.08
22 769 11.03
23 770 11.06
24 769 11.03
25 771 11.08
26 768 11
27 771 11.1 - 140 bar
28 772 11.13
29 772 11.13
30 771 11.1
31 777 11.26
32 772 11.13
33 773 11.15
34 773 11.15 - 130 bar
35 773 11.15
36 773 11.15
37 771 11.1
38 772 11.13
39 774 11.19
40 769 11.03 - 120 bar
41 771 11.08
42 771 11.08
43 774 11.19
44 774 11.17
45 769 11.03
46 775 11.22 - 110 bar
47 770 11.06
48 768 11.02
49 771 11.1
50 773 11.15
51 771 11.08
52 774 11.17
53 774 11.19 - 100 bar
54 772 11.13
55 773 11.15
56 777 11.28
57 773 11.15
58 772 11.13
59 767 10.98 - 95 bar
60 765 10.93
61 765 10.93
62 754 10.61
63 755 10.64
64 752 10.56 - 90 bar
65 749 10.48
66 744 10.32
67 737 10.12
68 726 9.83
69 710 9.48 - 85 bar

Max 777.00
Min 766.00

Ave 771.64

So, I'm happy that things are now going in the right direction. At the moment I'm not too concerned about the power but I would like to increase shot count. Any advice / ideas on what I should / could do to achieve this without upsetting the balance?