Disco SSG thread

[mooseslayer]

Time to start one. I have been working on an SSG for my .22 disco.  When I first got it I was disappointed with the 14 or so usable shots. In the past I have tried with my diy PA and some porting of valve, thinning poppit, and different tport sizes to try to get over 20 shots with jsb 15.9 at 800-850fps. I am a rookie at this and nobody up in my area that I know doing this stuff so flying by the seat of my pants.This  is just what I want for hunting small game. I have come close to it. I had drilled out my endcap long ago and threaded so I could change springs on the fly so Bob's first SSG was easy to adapt to. I tried Bob's first SSG 3inch and used my existing .040" thick springs in varying lengths but power dropped was first in mid 600fps. I made a new longer one and a couple of springs and even welded a 3/8 nut to the back of my endcap to be able to use the longer ssg before coil bind. I got back to 750fps and got a ton more shots. I am waiting on order for 10" long .312 springs n .037, .041. .047 and .055 for testing.

Here is the string I just shot jsb 15.9. almost at coil bind and small gap.

1 744
2 741
3 743
4 748
5 742
6 744
7 740
8 744
9 749
10 747
11 744
12 747
13 750
14 749
15 747
16 754
17 751
18 746
19 740
20 742
21 741
22 737
23 746
24 743
25 737
28 737
29 722
30 729
31 728
32 726
33 719

Not sure where to cut it off but I have never got near this many shots before the SSG.
Still want to get power back but this is a start. I made this really long bastardized SSG for testing and still ave the original 3" one. I am hoping to consolidate everything once I get new springs. I am sure I will get this shorter, but if I increase shot count dramatically and it sticks out the back, I will just make some sort of shroud for it.
Here is my bastardized version of SSG. It is under almost an inch of preload.

[mooseslayer]

Just as a reference, I was getting about 17-18 shots with same pellets at 810fps avg  before SSG. I dug up a string from last fall (been too cold to shoot here in southern Ontario).

797.00   821.00
797.00   819.00
800.00   817.00
805.00   802.00
810.00   812.00
   
813.00   805.00
813.00   799.00
820.00   786.00
825.00   
829.00   

[Airgun.Sniper]

 Play with spring weight or SSG tension maybe?


 Cheers

 Jay

[Hobbyman2007]

In case you don't already have it here is the best(imo) efficiency calculator . Seeing that it's free online, I don't think Lloyd would mind.
http://www.calc.sikes.us/1/

[mooseslayer]

oops...just realized I missed shots 26 and 27


Here is the string I just shot jsb 15.9. almost at coil bind and small gap.

1 744
2 741
3 743
4 748
5 742
6 744
7 740
8 744
9 749
10 747
11 744
12 747
13 750
14 749
15 747
16 754
17 751
18 746
19 740
20 742
21 741
22 737
23 746
24 743
25 737
26 744
27 737
28 737
29 722
30 729
31 728
32 726
33 719

[Rivers3Plinker]

So you lost some power but gained many shots. I think this is quite typical. To get it back, are you going to try stiffer springs since you're already at coil bind?
I have made one like yours using a Prod cap but haven't had a chance to test it yet. But.... I've already thought of a new design based on another version a vendor is selling for the Mrod. It will cost me more parts from Crosman in the way of another Prod hammer weight which I will have to machine for the rear breach screw for clearance but it will be all internal design. Also the weight from the rod is part of the total hammer weight.
I can't wait for the weather around here to break but I know it's going to be three weeks or so at least. You're north of me but not too far. I'm down in SW Michigan. Late March we should be back to shooting outdoors.

[mooseslayer]

I have springs ordered in .037 .041 .047 and .055 to test....and yes, hoping to increase power with them. I was hoping to see what others are doing with disco SSG in this thread. I love that it is evolving from Bob's first SSG.

[oldpro]

You do need a slightly stiffer spring with fewer coils. Your biggest problem is your spring has far to many coils and also try polishing your hammer tube with a ball hone it will add more FPS at no cost and make cocking smooth like gravy.

[Airgun.Sniper]

You do need a slightly stiffer spring with fewer coils. Your biggest problem is your spring has far to many coils and also try polishing your hammer tube with a ball hone it will add more FPS at no cost and make cocking smooth like gravy.

 I will have to save this tip and try it myself for sure. So less coils and hammer polish?

 Cheers

 Jay

[oldpro]

The hammer tube area as seen in first video here... http://wickedairrifles.com/installation-instructions.html

[mooseslayer]

I polished that area a while back but not sure how smooth. I think I used a dowel in drill with notch for sandpaper. Maybe ill do again. Got up to 1500 wet dry and some ultimox. Thanks Oldpro. Springs will be here next week

[Airgun.Sniper]

The hammer tube area as seen in first video here... http://wickedairrifles.com/installation-instructions.html

 Same thing applies for the disco Im assuming?

 THanks Travis

 Jay

[Rivers3Plinker]

The hammer tube area as seen in first video here... http://wickedairrifles.com/installation-instructions.html

Thanks Travis - I'm totally doing this to my Disco. Also my brother's Mrod when we tear it down next time.
Nice work on the Youtube vids and the online instructions by the way.

[Rivers3Plinker]

Follow up question - what grit do you use or recommend?
I'm looking at 400 grit.
And actually the Disco I believe is slightly smaller ID so I would assume a 1" is a little big.
I forget the dimension but I will measure mine first.
Thanks

[dpittman]

May try this on sons Disco. I measured everything in the air tube from the valve stem to the end of cap. Gun apart and spring out and measured everything with dial caliper. the total length from bottom of hammer hole to bottom of cap hole was 1.575 with hammer touching stem and cap sitting in tube. Can you take this length and subtract .020-.040 and make SSG that long. My spring at rest is 1.940 so it is being compressed around .365" when assembled. Will I need a new spring to do this. What end cap mods need to be made to try to keep it mostly internal. Any idea on when a WAR SSG will be available for Disco if I mess this up.

[wormbobskey]

Excuse my ignorance, but what does SSG stand for?

[mooseslayer]

A few months back, Bob Sterne designed and implemented a Spring Stop Guide, which basically stops the hammer spring just shy of the hammer when it opens the valve and reduces/eliminates hammer bounce, which in many cases is a huge waste of air. This makes the pcp more efficient and you can get more shots per fill. It is brilliant and I think the biggest rage lately as many are designing different and better versions of it. Do a search and you can find more information. I think the original thread is 38 pages long.

[mooseslayer]

Here is the original thread if you have some time to read 39 pages of posts lol.

http://www.gatewaytoairguns.org/GTA/index.php?topic=102095.0

[wormbobskey]

Thank you sir.

[Rivers3Plinker]

May try this on sons Disco. I measured everything in the air tube from the valve stem to the end of cap. Gun apart and spring out and measured everything with dial caliper. the total length from bottom of hammer hole to bottom of cap hole was 1.575 with hammer touching stem and cap sitting in tube. Can you take this length and subtract .020-.040 and make SSG that long. My spring at rest is 1.940 so it is being compressed around .365" when assembled. Will I need a new spring to do this. What end cap mods need to be made to try to keep it mostly internal. Any idea on when a WAR SSG will be available for Disco if I mess this up.

If internal design is your plan, the factory end cap should be usable.
It comes with a threaded bore for a spring guide or a de-gassing tool which could be used for an adjustable stop for the SSG rod.
With internal design. the SSG rod rides through the middle of the hammer weight and the end of the SSG rod on the face side of the hammer weight is actually what strikes the valve when you fire. This is how I understand it and until I build my own, I won't have any measurements or part suggestions. By then, Old Pro Travis will have his to market already. Tricky parts might be hardening the end of that rod which also must have a larger end on it. I'd like to turn this on a lathe and heat treat it ideally.
Or just by it from Travis when he releases it.