GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: Tommy on October 28, 2014, 11:40:08 PM
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The newer Discos have a stronger hammer spring. I got my .22 Disco in June from Norm. The string he shot started at 909fps and ended at 789fps for 13 shots. After doing a lot of reading I new what was going on. Too much preload on the hammer spring. Before i made the power adjuster I knew I had to reduce the tension on the hammer spring. I started with cutting off one coil and that gave me a few more shots. I knew it could do better. I then cut off two more coils and voila 30 shots. I then bought a chrony and found i was getting 30 shots at 775fps average within 4%.cool. Now I put in my power adjuster. I screwed it in to max {coil bind can,t cock then 1/2 turn out]I shot it over the chrony and got 20 shots at 850fps at less than 4%
Now I can adjust from all the way in to all the way out depending on what power i want.
Hope this helps some of the new Disco owners
Good luck
Tom
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Thanks Tom ,I have been breaking in to pcp's and just got a disco and I was looking for a simple solution to the short shot count.
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Tommy...do you know how long your spring+ guide is now? I made own pa and therefore modded a screw to be a spring guide. I will measure tonight but I think my cut spring with spring guide is under 2 inches now. I would love to know exactly what yours is as I have disco apart now and will be reassembling tonight.
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Thanks for posting that, I like simple direct solutions.
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Good to know. I have a Disco coming Friday. I wonder why a short spring turned in with a PA shoots the same velocity as the stock spring, but for more shots? I guess I don't fully understand the relationship between hammer spring and valve dwell.
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What grain pellet are you shooting Tom? As high as the numbers were I'm assuming 14 grain?
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I use 14.3 cphp
Tom
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Good to know. I have a Disco coming Friday. I wonder why a short spring turned in with a PA shoots the same velocity as the stock spring, but for more shots? I guess I don't fully understand the relationship between hammer spring and valve dwell.
Keep in mind the numbers he ended up with with the power adjuster are not nearly as high as what it started out at with the stock spring. His string started just over 900 but finished in the 700's. With the PA he started, and finished in the 700's.
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Good to know. I have a Disco coming Friday. I wonder why a short spring turned in with a PA shoots the same velocity as the stock spring, but for more shots? I guess I don't fully understand the relationship between hammer spring and valve dwell.
Keep in mind the numbers he ended up with with the power adjuster are not nearly as high as what it started out at with the stock spring. His string started just over 900 but finished in the 700's. With the PA he started, and finished in the 700's.
Good point.
So his string started at 900 without the modifications.
Let's say he turns the PA in until his string starts at 900 again. Will it be more consistent, or will it have the same decreasing string? Will it have a few more shots?
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Generally if you return to the previous high starting velocity the string should look the same (decreasing) with the same number of shots.... The fly in the ointment would be if the original setup was getting more air-wasting hammer bounce compared to the shortened spring (quite possible), in which case you might gain a few shots with the shortened spring.... However, tuning for a falling shot string is not, IMO, the way to go.... you want at the minimum a plateau to start, and preferably dial the power back a bit until the first shot is 3-4% below the peak and then stop shooting at 3-4% below the peak as well.... That is how the original Disco was tuned....
I haven't seen the "new" Disco hammer spring, but I wonder if Crosman used the one from a 2200?.... It is both stiffer and longer than the original Disco spring....
Bob
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yep What Bob said
Tom
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I consider my rifle to be one of the new ones with the stiffer spring everyone was talking about. This one is 2 inches long with 16 coils. I believe the spring is music wire and Is .039" wire diameter
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Thanks for the post. Just ordered a Disco (my first pcp) today. I've been compiling a list of things to look into and tweak after cleaning the barrel and getting it quiet.
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The original Disco springs were 0.035" wire.... so if yours is 0.039" they are not the same wire diam....
Bob
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II understand this and I wasn't disagreeing or stating otherwise. I was just simply stating the diameter and specs of my spring. so other people with similar issues or questions / concerns can read and see my comment
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II understand this and I wasn't disagreeing or stating otherwise. I was just simply stating the diameter and specs of my spring. so other people with similar issues or questions / concerns can read and see my comment
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I don't think Bob was saying you are wrong, just confirming that they are, in fact, different.
I wonder if one could find the part number for the old Disco spring, or if Crosman has completely phased that spring out.
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more likely they are still using the same part number.... even though they changed the spring....
Bob
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I apologize for the misunderstanding. And if they changed the part without changing the part number then I would check ebay or amazone for .22 disco hammer springs. Most of them do not have the specs of the springs but occasionally you'll run across one with the specs of the old spring. The old lighter spring came in today and this allows me to shoot at a wider variety of velocities. It FIXED my sudden velocity drop after 1400 psi. Bob suggested I replace my hammer spring and what do ya know. Smother closer groups. I believe the (bell curve) is fixed now. Once again thanks bob.
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Good thought Jeremy. But keep in mind that a seller might be selling new springs and has not updated the specs.
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True, for more variety in fps in go with the old springs, and a adjuster allow trait shot strings. Just go my orders in I'm happy.
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This seems like a good place to stick this.
I had a chance to shoot a few shots through the chrony before running off to work.
Starting at ~1500 PSI
892, 871, 849, 844, 836
Abysmal SD of 22.8
Then I ran out the door.
Looking forward to tuning it once I have my BNM goodies on it.
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I see alot of new Disco owners that would benefit from my thread. I am just wondering how we could make it more easily accesable.
Tom
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I see alot of new Disco owners that would benefit from my thread. I am just wondering how we could make it more easily accesable.
Tom
A link to it would be nice, seen you mention it a few times, as you post some info helping someone post the link as well, that way they can just click it and go rite to it!
William
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I see some more new disco owners that are not getting good shot counts .This thread would be a big help to them. Unfortunately i do not know how to post link in replys
If someone could help me out it would be appreciated. I think we can help alot of people.
Tom
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The 4 new Disco springs I just bought from Crosman must be old stock as they are .035 wire.I was hoping they would be the stronger spring.
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Thought I'd post my new results. I chopped 1.5 coils off of my spring and here are my results.
I am getting 25 shots from 858 fps to 842 fps w/ 10.5 grain CPUM. From 1950 psi to 950 psi.
AVG 848.85, ES 16, SD 4.6
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The 4 new Disco springs I just bought from Crosman must be old stock as they are .035 wire.I was hoping they would be the stronger spring.
Disco R Us sells a .040" spring...
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The 4 new Disco springs I just bought from Crosman must be old stock as they are .035 wire.I was hoping they would be the stronger spring.
Disco R Us sells a .040" spring...
Thanks,Bill
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I see some more new disco owners that are not getting good shot counts .This thread would be a big help to them. Unfortunately i do not know how to post link in replys
If someone could help me out it would be appreciated. I think we can help alot of people.
Tom
If you want to put a link in a space like this, just open the website, highlight the address line, right mouse to get to "COPY". Then all you have to do is click in this space and right mouse again to select "PASTE". You might want to practice a little first like in e-mail to yourself. https://video.search.yahoo.com/video/play?p=a-team+plan+comes+together&vid=303aa4da65d560417e19a795b53835bd&l=00%3A15&turl=http%3A%2F%2Fts3.mm.bing.net%2Fth%3Fid%3DVN.607997352948337670%26pid%3D15.1&rurl=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DFPQlXNH36mI&tit=A-team+Hannibal&c=0&sigr=11af6demm&sigt=10f0tadet&back=https%3A%2F%2Fsearch.yahoo.com%2Fsearch%3Fei%3DUTF-8%26p%3Da-team%2Bplan%2Bcomes%2Btogether%26fr%3Dyfp-t-745-s&sigb=12kf6m1fo&ct=p&pstcat=arts+culture+and+entertainment&age=0&&tt=b (https://video.search.yahoo.com/video/play?p=a-team+plan+comes+together&vid=303aa4da65d560417e19a795b53835bd&l=00%3A15&turl=http%3A%2F%2Fts3.mm.bing.net%2Fth%3Fid%3DVN.607997352948337670%26pid%3D15.1&rurl=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DFPQlXNH36mI&tit=A-team+Hannibal&c=0&sigr=11af6demm&sigt=10f0tadet&back=https%3A%2F%2Fsearch.yahoo.com%2Fsearch%3Fei%3DUTF-8%26p%3Da-team%2Bplan%2Bcomes%2Btogether%26fr%3Dyfp-t-745-s&sigb=12kf6m1fo&ct=p&pstcat=arts+culture+and+entertainment&age=0&&tt=b)
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Thank you Mike
Tom
I will try again later
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Woah! I just got done tuning my buddy's Disco with him and we got some crazy results!
We cut two coils off the hammer spring, then put a thick o-ring behind the head of the valve stem (inside the valve). He is getting 50 shots from 850 - 825 fps. It is a stunning bird buster. We just took it out back real quick and both of us dropped a bird with a single shot before it got dark.
I don't know why it works, but it does!
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Woah! I just got done tuning my buddy's Disco with him and we got some crazy results!
We cut two coils off the hammer spring, then put a thick o-ring behind the head of the valve stem (inside the valve). He is getting 50 shots from 850 - 825 fps. It is a stunning bird buster. We just took it out back real quick and both of us dropped a bird with a single shot before it got dark.
I don't know why it works, but it does!
Pics please!
Do you know what O-ring it was?
Is that with 14.3 gr pellets?
What psi fill are you using?
Joseph
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Joe, it was a tiny o-ring from my random parts bag. So, no help there.
It is a .177 shooting 7.9 grain pellets. So, not a ton of power, but it is acting like a regg'd pcp.
We are using a 2000-1000 psi fill. Strangely, the velocities are consistent across a full 1000 psi of air.
It's like a poor man's regulator or something.
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Can anyone help me out I am pretty confused with the results I got earlier.Using the crosman premier hollow points 14.3 grain I got a high of 795 a low of 711 and an average of 773 over 20 shots,standard deviation of 18.7 fps.Super inconsistent !I am using a stock disco spring with a few coils cut off but last night I decided to stretch it out for more power.Before I stretched it it was much more consistent but the velocities were a tad lower.I am looking to get mid 800's for about 20 shots.The polymags were a little more consistent but not by much.Really all I've done to the gun is a power adjuster,3 screw trigger mod,and a brass trigger blade.
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Try screwing in the pa more Mine seems to bind a little halfway making it feel bottomed out. Is there a spring guide in yours? I can screw mine in all the way till it doesnt cock. Then I bring it out 1/2 for my highest power.
Hope this helps
Tom
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Try screwing in the pa more Mine seems to bind a little halfway making it feel bottomed out. Is there a spring guide in yours? I can screw mine in all the way till it doesnt cock. Then I bring it out 1/2 for my highest power.
Hope this helps
Tom
Can you take picture of where your power adjuster is at?I do have a spring guide in mine btw.
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You have to make a PA. I made mine from a 1.5" 10-32 bolt with a wingnut screwed on and a nylon insert nut in front of that.
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You have to make a PA. I made mine from a 1.5" 10-32 bolt with a wingnut screwed on and a nylon insert nut in front of that.
I have a power adjuster on it.
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Sorry, my bad. I misread your post. Mine is 2 turns in from no tension.
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Can you turn it in to where it doesnt cock?AGH
Tom
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I see some more new disco owners that are not getting good shot counts .This thread would be a big help to them. Unfortunately i do not know how to post link in replys
If someone could help me out it would be appreciated. I think we can help alot of people.
Tom
Here Tommy is a link to a video I made for you, that shows how to post a link from the GTA forums. This will work for any internet link of specific forum post, such as a link to a particular post from your profile page.
Just click the You Tube link below. You may have to turn up the volume and watch in full screen to see it better!
http://youtu.be/jUDQzbM4V48 (http://youtu.be/jUDQzbM4V48)
William
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Can you turn it in to where it doesnt cock?AGH
Tom
Yes.
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The newer Discos have a stronger hammer spring. I got my .22 Disco in June from Norm. The string he shot started at 909fps and ended at 789fps for 13 shots. After doing a lot of reading I new what was going on. Too much preload on the hammer spring. Before i made the power adjuster I knew I had to reduce the tension on the hammer spring. I started with cutting off one coil and that gave me a few more shots. I knew it could do better. I then cut off two more coils and voila 30 shots. I then bought a chrony and found i was getting 30 shots at 775fps average within 4%.cool. Now I put in my power adjuster. I screwed it in to max {coil bind can,t cock then 1/2 turn out]I shot it over the chrthink ony and got 20 shots at 850fps at less than 4%
Now I can adjust from all the way in to all the way out depending on what power i want.
Hope this helps some of the new Disco owners
Good luck
Tom
Good info Tom. Messing with the spring and things will have to wait for me to even get familiar with this unknown animal. As much as I thought I would like to have something like the R9, 48, 52 etc as a starter, I think from all the reading that this was a good choice to start and decide. I do have the old Crosman Storm XT and I can play with it still around the house. I believe the Discovery will be a serious small game hunter for me. I did a trigger modification on the Storm with a washer after watching a little potty mouthed genius on YouTube. It did make it better.
Mike
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The newer Discos have a stronger hammer spring. I got my .22 Disco in June from Norm. The string he shot started at 909fps and ended at 789fps for 13 shots. After doing a lot of reading I new what was going on. Too much preload on the hammer spring. Before i made the power adjuster I knew I had to reduce the tension on the hammer spring. I started with cutting off one coil and that gave me a few more shots. I knew it could do better. I then cut off two more coils and voila 30 shots. I then bought a chrony and found i was getting 30 shots at 775fps average within 4%.cool. Now I put in my power adjuster. I screwed it in to max {coil bind can,t cock then 1/2 turn out]I shot it over the chrony and got 20 shots at 850fps at less than 4%
Now I can adjust from all the way in to all the way out depending on what power i want.
Hope this helps some of the new Disco owners
Good luck
Tom
Does reducing the power also reduce the loudness without a TKO or similar attachment?
Mike
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Does reducing the power also reduce the loudness without a TKO or similar attachment?
Mike
Yes it will reduce the Noise, but probably not a significant amount, it may make it more backyard friendly but maybe not!
William
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http://www.micromark.com/coil-mandrel-set-package-of-8,9559.html (http://www.micromark.com/coil-mandrel-set-package-of-8,9559.html)
This would be helpful for making new springs!
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Does reducing the power also reduce the loudness without a TKO or similar attachment?
Mike
Yes it will reduce the Noise, but probably not a significant amount, it may make it more backyard friendly but maybe not!
William
Thanks William.
Mike
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Could someone explain the term "power adjuster" in connection with the Discovery power and hammer spring discussion. Are they commonly available? Thanks
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Could someone explain the term "power adjuster" in connection with the Discovery power and hammer spring discussion. Are they commonly available? Thanks
The Disco power adjuster or Rear Velocity Adjuster (RVA) is a device that screws inward on your hammer spring putting more tension on it, therefore pushing the Hammer harder making it open the air valve further as well as holding it open longer giving more air and flow to the pellet increasing FPS. Very easy modification and you can get one from Disco's R Us. Below is a link and a pictue of what it looks like, some look a little different but all serve the same purpose. This is a mod and does not come factory with the Discovery.
Pre-load adjuster Discos R US http://discosrus.net/disco/ (http://discosrus.net/disco/)
The Pic below is a little different than the normal one, but gives you an idea of what it looks like and how it works!
(http://www.bigedmachining.com/BigEdAdj2.jpg)
William
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On the discos r us page it lists a spring preload adjust (power adjuster) but also has a "stroke adjuster" that you can purchase seaport or as part of the bundle...
What is this stroke adjuster?
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On the discos r us page it lists a spring preload adjust (power adjuster) but also has a "stroke adjuster" that you can purchase seaport or as part of the bundle...
What is this stroke adjuster?
A stroke adjuster is a screw that is on the front end of the hammer that hits the valve when the hammer goes forward. The stroke adjuster goes through the hammer and can be adjusted from the rear of the gun by inserting a long allen hex key in and turning it to make the hammer shorter or longer. When you screw that screw in making it longer the hammer will not travel as far before hitting the valve and if you turn it back making it shorter that gives the hammer more distance to travel therefore picking up momentum and speed before it hits the valve stem, when this happens it pushes the valve open further allowing more air to escape which means more power to the pellet.
This will allow you to finely tune the Air gun to get the FPS needed to push the pellet at the speed it likes best making it more accurate or just for lower the power for more shots per fill or raising the power level for heavy duty hunting or long distance shooting as long as the pellet stays stable at the power you set it.
Use the Rear spring load adjuster in sequence with the stroke adjuster to finely tune your AG.
William