35 shots per fill Disco shot string

[William]

Those are some really nice strings on those Disco's. Perfect for lots of shots for targeting or small game at moderate ranges. Just think those are from a 2000 PSI fill and still getting good FPS for plenty of enjoyment, that tank of air will last a long time or just plain easier to pump it up if using a hand pump!

I do know if I turn mine down to about those specs with my Double tube Disco it seems like it will never need another fill!

Good job 

William

[Martis 1]

Hmm, interesting to see the varying results.  I played with a lighter spring and PA from a Challenger and didn't care for the results.  I ended up cutting a couple coils, (don't recall now how much), off the factory Disco spring and going back to the factory end cap with no PA.  Now, with 18.1 gr. JSB's, I'm getting 18 shots that start and end at 730fps.  Accidentally threw away the paper with the chrony results, so can't say exactly what the shot string was. 

Seems like I should be getting more shots at that velocity, but maybe not. 

I'm wondering if clipping another coil or more off, and installing a PA made from a screw and rivet, would be of any benifit?  Are there other things I should be looking at to make the gun more effecient?

Accuracy's fine, so don't want to mess that up...

Ron.

[Tweeter]

Would a 2240 hammer spring work in a disco with a PA?  Or would it be way too light?

[tjcib]

Hmm, interesting to see the varying results.  I played with a lighter spring and PA from a Challenger and didn't care for the results.  I ended up cutting a couple coils, (don't recall now how much), off the factory Disco spring and going back to the factory end cap with no PA.  Now, with 18.1 gr. JSB's, I'm getting 18 shots that start and end at 730fps.  Accidentally threw away the paper with the chrony results, so can't say exactly what the shot string was. 

Seems like I should be getting more shots at that velocity, but maybe not. 

I'm wondering if clipping another coil or more off, and installing a PA made from a screw and rivet, would be of any benifit?  Are there other things I should be looking at to make the gun more effecient?

Accuracy's fine, so don't want to mess that up...

As always, the question is: "What do you want to use it for?"

Starting and ending at 730 fps means your maxing out velocity at about 760 (assuming 4% spread). That is a lot more power over the full shot string than what I described in the original post. Anywhere from 5-10% additional energy (if my math is correct). As always, more energy means more air.

I imagine you could easily set a goal and meet it by detuning and using a PA to bring it back up to your goal.

[tjcib]

Would a 2240 hammer spring work in a disco with a PA?  Or would it be way too light?

It's all about physics. You could use a lighter spring, or a lighter hammer, or both, or a heavier spring with a lighter hammer. You find guys using all kinds of combinations.

It all really just comes down to f=ma

However you get there is up to you. Other guys could maybe chime in about specifics. I've been happy with cut stock spring. Tried a heavier spring and didn't like it so much.

[Edtampa]

Thanks William,

I think my next thing will be a Blaster stock especially after seeing yours!

[Martis 1]

If I get time today I think I'll set up the chrony and shoot a string.  I accidentally threw out all my notes, but there was something about the shot string that I wasn't happy with, just can't recall now.  I had also tried a lighter spring and a PA out of a challenger.  If I recall correctly, even down in the 600 range, I wasn't getting any more than about 20 shots.  Then I somehow managed to screw up the PA so it won't screw in or out.  Pulled all that off, clipped the original spring, and called it good. 
I posted a thread about it, and I recall someone said it didn't sound like my Disco was shooting efficiently.
Guess I can either leave it be, or start from scratch again...
Ron.

[Ribbonstone]

Can get a 30-40 shot string (under 4%) with a Discovery at about 20 foot pounds (call it 19-20), and there is an added bonus: using 1/2 the air per shot certainly makes it a good bit quieter. All in all, 20 foot pounds well suits the Discovery.

[Tweeter]

I clipped 2 coils off my stock spring and took a few shots over the chrony but it gave me readings in the 950's so I stopped because light was fading and was standing too close to my chrony to avoid shooting it.  Theres no way It shoots that hot.  Roughly what setting will get me 30-40 shots at 20fpe?  I would be thrilled with them numbers!

[Tweeter]

Should I try turn the screw in until it won't cock and then back it off a couple turns and shoot a string?  Is this just a trial and error process because everyone's springs will vary after they clip coils off?

[Ribbonstone]

Should have been clear: a .22 Discovery.

In my case:

Lighter striker spring (about 2 1/2 coils cut from a standard spring).
Striker weight reduced by about 20-25%.
Power adjuster in order to set the spring tension.


Ends up averaging 19.4-20.2 foot pounds (depending on pellet weight) at 4% (the heavier pellets end up earning BOTH a little more energy and a few more shots per 2K-1K fill).

[Martis 1]

Should have been clear: a .22 Discovery.

In my case:

Lighter striker spring (about 2 1/2 coils cut from a standard spring).
Striker weight reduced by about 20-25%.
Power adjuster in order to set the spring tension.


Ends up averaging 19.4-20.2 foot pounds (depending on pellet weight) at 4% (the heavier pellets end up earning BOTH a little more energy and a few more shots per 2K-1K fill).

I'm thinking that by lightening your striker weight, you've gained a big advantage over me.  I'm getting something like 21 foot pounds with the 18.1 grain pellet, but only for 18 shots.  That's with a clipped factory spring, and everything else stock.
Ron.

[Tweeter]

This is the string I just shot with cphp 14.3's.  I didn't use any preload on the spring just clipped 2 coils off.  Shot from 2000psi down to about 900 so it seems I will get about 20 shots.  Will I benefit from shortening the spring more or adding tension with the PA?

[Tommy]

I just shot this string. I would call it my medium range' 14.3cphp 2200 psi fill a new full length spring and a new power adjuster
I got a new valve and made the exhaust hole .160 and angled the bottom of it back a little at the bottom of hole. I then took fine sandpaper and cleaned out the tp a little
845.2
860.5
853.2
863.9
858.8
866.4
876.4
875.6
873.0
882.0
890.0
887.2
886.0
888.1
887.2
881.2
880.6
881.1
874.2
856.0
859.5
843.3
Ending at 1200psi
Like I said this would be my medium setting meaning I can add or decrease tension and gain more shots or more power
Tom


Is this a good string?I would like to compare to others

[William]

This is the string I just shot with cphp 14.3's.  I didn't use any preload on the spring just clipped 2 coils off.  Shot from 2000psi down to about 900 so it seems I will get about 20 shots.  Will I benefit from shortening the spring more or adding tension with the PA?

Justin,

Your just so close to being there it isn't funny! To get 20 shots like you are showing at that FPS it pretty darn good for a Disco. If you want less power and more shots lower the fill and ease off the spring a little at a time, you may not have to cut the spring.

Personally I would leave it alone and drop the fill pressure a little very little.

Wish my stock Disco did what yours is doing at them settings 

William

[Martis 1]

Ok, I don't know where I got the 730 fps, and I don't think my disco is very efficient, I dunno.  Here's today's shot string, starting with 2,000psi per the pumps gauge.  The gun's gauge is reading higher at that fill. 

1)711.7                                          9)712.8                                        17)712.3                                                         
2)708.5                                        10)715.0                                        18)703.2
3)715.2                                        11)715.0                                        19)697.7
4)708.0                                        12)717.2                                        20)691.9
5)711.3                                        13)716.6                                        21)685.9
6)712.8                                        14)715.1
7)711.6                                        15)713.8
8)713.1                                        16)710.5
 
I can live with this, but it sure seems like at this velocity, I should be getting a lot more shots per fill.  What do you guys think?  Is there something else I should be looking at?  It's not blowing air out the bolt, and it holds air forever.
Ron.                                     

[Tweeter]

Thanks William, I will try dropping the fill pressure a bit and see if that tightens the numbers up some.  Then I'll just shoot it and shoot it and shoot it...   
  Martis,  that to me looks like a very consistent shot string,  I am still learning how to "read" shot strings but I don't think there is anything wrong with your Disco.  What weight pellets did you use to chrony?

[Martis 1]

Thanks William, I will try dropping the fill pressure a bit and see if that tightens the numbers up some.  Then I'll just shoot it and shoot it and shoot it...   
  Martis,  that to me looks like a very consistent shot string,  I am still learning how to "read" shot strings but I don't think there is anything wrong with your Disco.  What weight pellets did you use to chrony?

Those are with the 18.1 grain JSB's.  They hit really hard, and I'm pretty happy.  I'm just thinking maybe there's an air leak or something somewhere. 
If you showed me this shot string and said this is what an average Disco does, I'd still buy it in a heartbeat, but if others are doing better, and I can improve mine, I wouldn't mind playing with it.

[William]

Thanks William, I will try dropping the fill pressure a bit and see if that tightens the numbers up some.  Then I'll just shoot it and shoot it and shoot it...   
  Martis,  that to me looks like a very consistent shot string,  I am still learning how to "read" shot strings but I don't think there is anything wrong with your Disco.  What weight pellets did you use to chrony?

Those are with the 18.1 grain JSB's.  They hit really hard, and I'm pretty happy.  I'm just thinking maybe there's an air leak or something somewhere. 
If you showed me this shot string and said this is what an average Disco does, I'd still buy it in a heartbeat, but if others are doing better, and I can improve mine, I wouldn't mind playing with it.

Its hard to say what an average string is on a Disco, seems like the newer ones have a stronger spring than the older ones do, mine new 2 years ago or so, was in the mid High 700 FPS range with 20 shots or maybe a little more. Any Disco that is pretty much out of the box with the older slightly weaker original hammer spring will be in the 760-780 FPS range with 20 - 25 shots per fill. The newer ones that somehow got the stronger spring on the hammer are around 900 FPS and only 10 - 12 shots per fill.

A good tuned disco for 15 shots is going to be pushing 15.9 JSB's at 880 FPS or a little higher. If it is getting 25 shots its around the 700 FPS mark as mentioned above. If it is getting 30 to 35 shots it is tuned at around 625 FPS.

You can get a Disco to shoot good in about any FPS depending on pellet used, but my Disco's prefer 15.9 grain JSB's at 825 to 940 FPS and will stack pellets under dimes all day long at 40 yards,,, well sometimes,,, lets not kid anyone here, not even the best shooter is that good at 40 yards, if so prove it,,, then I make offer $$$ for gun lol.

My Disco's will shoot any and all JSB's almost perfect every time no matter the weight, but the 15.9's are the best at 920 FPS for 25 to 30 shots and double tubed, but I am shooting a 3000 PSI fill, the gun is modified for safety to take a higher fill and is regulated at 1800 PSI.

Food for thought, have you tried the 13.43 grain Domed JSB's? they sometimes out shoot anything I have tried in a Disco!

The Disco, one of the best little guns around 

Boys they aint nuttin you can't do with a Disco, from pesting flies to killing hogs with a modded .30 cal barrel on it   

Just pick your pot and a Disco can fill it 

William

[Ribbonstone]

MArtis 1:

Pretty good shot count.  Do think you could get another 4-6 shots. 

IF your run from #12 to #20 is acceptable, then you would be able to start at 685-688 and work up at the start...which  could amount to 4-5 shots at the front end of the shot count.

Thing is, to do that, would either have to:

A.Retune the gun slightly to a little lower striker spring tension in order to stay at a 2000psi max fill pressure and gain those early shots.

B.Leave the setting alone and fill to more than the recommended 2000psi (lets say to 2100-2200psi), testing along the way until the velocity reads about 685 for the first shot.

C.Lighten the weight of the striker (which decreases the force of the hit to the valve...like choice A...but also tends to save a little air in the process).


Persoanlly, I tend to stay at or below 2K just to keep to one of the nice concepts of the rifle and go with either A or C.  Others here fill to 2.1-2.2K.  Tempting in your case as you would have to do NOTHING to the rifle.