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PostPosted: Mon Mar 07, 2016 5:56 pm 
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Joined: Wed Sep 10, 2014 2:42 pm
Posts: 147
Location: Ontario
Ok...some preliminary testing with new springs. There are so many factors that can vary the results so I started with a goal of about 800fps with jsb 15.89 to get me about 22 -23 fpe on disco .22
The .037 springs too light...was in high 600fps range with a 3" spring so didn't even shoot strings.
The .041 spring I did a couple quick tests which were similar to my first ones with .040 so I decided to leave and test more later.

On to the .047 springs...started about 3" long so lots preload, very hard to cock mid 800fps but descending string, so start cutting coils and trying until I got just over 800fps and strings not descending. I ended up with 2.35 inch long spring and started testing.

Test 1 - fair amount of preload, close to coil bind, small gap 2300 - 1400 JSB 15.89 2.35, .047 spring

1-813 11-821 21-806
2-816 12-819 22-805
3-818 13-820 23-800
4-821 14-821 24-802
5-820 15-819 25-793
6-819 16-814 26-788
7-813 17-810 27-787
8-819 18-818 28-782
9-821 19-809
10-821 20-811

Test 2 - same preload, dial in nut on SSG to create bigger gap 2300 - 1500 JSB 15.89 2.35, .047 spring

1-795 11-809 21-807
2-797 12-812 22-807
3-800 13-813 23-799
4-796 14-814 24-801
5-802 15-815 25-795
6-808 16-808 26-792
7-808 17-807 27-788
8-805 18-809 28-786
9-807 19-806 29-784
10-807 20-805 30-777

Test 3 - dial out nut 1 more full turn so bigger gap 2300 - 1400 JSB 15.89 2.35, .047 spring
Note ...all my adjustments one full turn on bolt (preload) and nut (gap so there is a lot of room for minor adjustments to meet your specific goal. Changing the gap here didn't do a lot.

1-792 11-800 21-803
2-798 12-803 22-805
3-808 13-814 23-795
4-799 14-815 24-802
5-801 15-809 25-803
6-798 16-799 26-790
7-793 17-801 27-792
8-804 18-796 28-786
9-795 19-800 29-774
10-799 20-808 30-768

Test 4 - dial 3/8 bolt out one full turn easier to cock, less preload, small gap 2300 - 1400 JSB 15.89 2.35, .047 spring
Less power but more shots...I kinda like this string and near my goal and very consistent.

1-774 11-776 21-779 31-777
2-768 12-783 22-778 32-777
3-775 13-775 23-778 33-776
4-772 14-780 24-779 34-777
5-771 15-782 25-779 35-768
6-780 16-772 26-780 36-771
7-771 17-783 27-779 37-764
8-774 18-782 28-776 38-763
9-783 19-786 29-783 39-761
10-777 20-785 30-777 40-757

Test 5 - same preload as #4 but 1 full turn gap 2300 - 1400 JSB 15.89 2.35, .047 spring

1-771 11-775 21-782 31-768
2-773 12-782 22-787 32-768
3-783 13-781 23-782 33-765
4-770 14-777 24-782 34-764
5-778 15-782 25-783 35-758
6-774 16-783 26-778 36-760
7-779 17-784 27-777 37-754
8-774 18-783 28-770 38-747
9-773 19-778 29-777
10-772 20-783 30-778

That's all I have time to test for now, but same spring, just change preload and gap. I will try one more turn out on bolt if I have the room, which will probably drop me closer to 750fps and then decide whether to clip another coil on the .047 spring and test some more. Then a quick try with the .055" spring, which I think will be too strong, and back to testing the .041 spring.


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PostPosted: Sat Mar 12, 2016 3:23 pm 
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Joined: Fri Feb 26, 2016 2:42 pm
Posts: 50
you, sir, are an epic genius.


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PostPosted: Sun Mar 13, 2016 8:05 pm 
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Joined: Wed Sep 10, 2014 2:42 pm
Posts: 147
Location: Ontario
I am just copying Bob Sterne's brilliant idea. It was finally warm enough outside today to shoot a little.
I shot a string with JSB 15.9 and the .047 spring and a 770fps avg setup. I cut down my SSG rod length and 3/8 bolt to streamline a little. I got another good string with 35 shots and was nice and accurate. I want to test some more so I left the bolt longer than I need for now.
I then did test with a 2.25" long .055 spring (very strong spring) It was a bit of a bust because even with almost no preload it was extremely hard to cock. I actually used a short piece of pipe over the bolt handle to be able to do it. I did get 24 shots with an 830 average or 24.3fpe but I would have to make a big bolt handle in order to cock the gun.

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PostPosted: Mon Mar 14, 2016 12:52 am 
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Joined: Wed Oct 17, 2007 3:27 am
Posts: 2585
Location: Winnipeg, Canada
775-ish in .22 is pretty decent, especially for hunting purposes.

My non-Crosman .22 pcp tops out around the 760 mark, (with the 18.1 JSB heavy) and I've decided to leave it there~ even with the delrin valve stem, I'm not liking much more hammer spring tension than what I'm using. I have not done anything to buffer the hammer spring (yet), but doubt I'm losing any excess air.

Just wondering how well that disco valve of yours is going to stand up to that much pre-load?


Regards,

Doc Sharptail

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"Ain't no half-way"
-S.R.V.


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PostPosted: Sat Sep 17, 2016 7:05 pm 
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Joined: Mon Aug 24, 2015 4:56 pm
Posts: 462
Location: Tecumseh, Ontario in South Western Ontario
This why I bought the disco. It's so freakin tunable. Oh yes Bob's invention the SSG is in the parts collecting phase. I have a Challenger adjustable hammer coming. I don't know if I'll order an RVA or build one. Any spring diameter and length is still on the table. Double disco, valve enhancement it's all possible.
One thing I'm really happy about is the accuracy is crazy good even though I've only tested in my 15 yard basement range. I know these clichés get tiring but every shot through the same ragged hole. I was wondering if I forgot to load a pellet :lol:

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Ed.


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PostPosted: Sat Sep 17, 2016 7:31 pm 
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Joined: Wed Sep 10, 2014 2:42 pm
Posts: 147
Location: Ontario
Good to hear. SSG is awesome. Glad to hear the disco is shooting nice. Mine does as well. Trying to get it fine tuned for grouse. Heading up north moose hunting in 12 days so want it dialed in.


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