Some Disco questions

[justkillurself85]

Alright so I've been intersted in the Disco for a little while now, but had some questions about it and also charging it. What is the max pressure the gun can handle and is there a way to get it to handle, say, 3000psi?

I've been looking at all the parts available for it and I really like the different options for customizing it. I got to thinking though that if I did get a Disco, I would for sure customize it. Now, can I put one together from scratch? Buy the custom parts I would want and then buy the stock parts (new) to complete the build??? Actually are there enough custom parts available to where I wouldnt have to buy any stock parts???

What I really dont understand is why the carbon fiber 4500psi tanks are so much? I can get a 90ci 4500 paintball tank for under $200 (I know it wont work, just saying) yet the SCBA 4500 tanks start at $400 for a tiny tank (Guppy for example). What gives?

I saw somewhere on here that I can take a Ninja paintball tank and shim the regulator or something and get it to around 2000psi output. Could someone give me a link on how to do that? It sounds like the way to go with the Disco. Unless I can somehow get it to 3000psi, then I might have to figure out another (cheap) option.

[sawtoothscream]

i put a heavier hammer spring in mine and i pump it to the end of the yellow which i think is 2400psi. gun handles that fine and is a real shooter.  i personally  would try to pump it to the red of the red.  sure someone else can give you more info

[Ribbonstone]

2K is the recommended fill, and while some go higher, going to 3K might be unwise. Doubt it would self destruct, but I'm not too pleased with the two phillips screws used for valve retention.

Basically, if you want a gun rated for 3K pressure, would be best to buy something other than a Discovery.

Carbon fiber tanks are a good bit more complicated to make, which is one reason they cost more...but suspect at least some of it is that the fast majority of them are sold to agencies that buy with tax money.

[roachcreek]

I built this one from scratch, started with a 2240 and rplaced everything with mostly Disco, it had a cut down 14 inch Disco tube, M4 stock and stock port/ hammer spring adjuster a Boss Disco valve, Blue forks grip frame, Hogue grip, RIm 8 shot magazine on a Anthony J breech.

The build was a lot of fun.

I filed to 3000 PSI, which seemed safe at the time with the bust pressure of the Disco tube tested at past 7000 PSI and got one magazine full at 20 FPE with 22 JSB Monsters.

It was a very fun hunting carbine for around the house.

[justkillurself85]

I built this one from scratch, started with a 2240 and rplaced everything with mostly Disco, it had a cut down 14 inch Disco tube, M4 stock and stock port/ hammer spring adjuster a Boss Disco valve, Blue forks grip frame, Hogue grip, RIm 8 shot magazine on a Anthony J breech.

The build was a lot of fun.

I filed to 3000 PSI, which seemed safe at the time with the bust pressure of the Disco tube tested at past 7000 PSI and got one magazine full at 20 FPE with 22 JSB Monsters.

It was a very fun hunting carbine for around the house.

I thought Disco came stock with 20fpe and with some work u could up em to 30+?

Alright so some how I missed this but the paintball tank is 90 cubic INCH and the Guppy is 17 cubic FEET. How many refills could I get out of each of them if I charge to 2400 and shoot down to, idk, 1200psi?

I was lookin around trying to put a parts list together, cant seem to find a barrel or compression tube. Anyone know where I can find em.

[Snaab9-2]

The disco does come stock with 20+ FPE and with a little work 30 FPE is easy to reach.

resterne has some really good info on Disco's and has posted some really nice graphs on here with a heavier hammer spring and 2400 psi.

[Ribbonstone]

Don't get me wrong...am NOT afraid the Disco tube will fail at higher pressure (in fact, believe it is the same material they use to make P-Rod and 1700/1701 3K tubes).

But do yourself a favor...if thinking about going over 2k with a Disco, swap out those cheezy phillips head screws for a top rated replacement.

[roachcreek]

Yeah I know the stock Disco will beat 20 FPE, but I had a 14 inch barrel on mine.

[rsterne]

I use 2400 psi fills (top of the yellow on the gauge).... but I wouldn't go higher.... I figure yellow means caution and red means stop, so that's what I do.... Without changing out the hammer spring for a heavier one (or at the very least fitting an RVA) you will lose velocity by filling over 2000 psi....

BTW, there are actually three 8-32 screws locating the valve, not two.... there is one on the bottom.... I don't know where you can purchase high strength 8-32 screws with a 5/16" OD head which is what is required on a Disco.... It is the side of the head that touches the tube, not the shank.... That is to spread the load over a wider area of the relatively thinwall tube.... If anyone knows a source for replacement screws please let us know.... I'd purchase them for sure....

Bob

[justkillurself85]

Yeah I know the stock Disco will beat 20 FPE, but I had a 14 inch barrel on mine.

My bad I thought u were talking about a 14" compression tube or air tube (whatever its called). Thats what 10" loped off the barrel? How was ur accuracy?

I cant seem to find out how to calculate how many fills I can get out of a 90ci 4500psi paintball tank. So far all the calculators are in cubic feet.


Can someone post a pic of these screws?

Still trying to locate a barrel and compression tube for a Disco.

[clip]

Why not just START with a rifle that's rated for a 3000 fill? There's a lot of 'em around and most all of 'em can be customized anyway, can't they? That way you'll begin with a safe platform.
  Just a thought....
   Larry

[roachcreek]

Bryan and Associates in South Carolina can cut down a tube for you and install the valve, or install a Boss valve, which is what I had.  A stronger hammer spring will open that valve at 3000PSI with no trouble, the tube is rated far heavier than 3000PSI altho the little gauge does show yellow or red at a lower pressure.. 

When they tested those tubes they did notice that the screws did take a seat to the side of the holes when they neared 7000PSI, so the valve did move or settle in, but was in no danger of letting go.  These parts are safety rated at three times, meaning if you have a fill level of 2000 PSI the part must be good for 6000 PSI, the Disco tube has been tested at over 7000 PSI.

Bryan and Associates can install that valve and I highly recommend they do it for you, it is tricky to get it done the first couple of times without cutting the orings.  That way you will get it in correctly, and you will get the screws in for you at the same time. Also have him put in a HPA fill nipple.

Cothran can make you a stainless steel Disco tube with the three valve retaining holes and it will be far stronger.  Being able to fill to 3000 PSI gives you a far better shot string. If I was doing it again, I personally would leave off the gauge on a custom made tube, they are totally inaccurate at that size, and on such a short shot count you should be able to count your shots.

You can pick up a Crosman 2240 grip frame for a song on the yellow or order it from Crosman, or just buy a used 2240 or a refurbished one for around $40.00.  You can use the hammer out of the 2240 on your build.

Charles Mellon will sell you a adjustable hammer spring/M4 stock port so you can use a M4 paintball stock on the rilfe.  I used a Anthony J aluminum breech on mine, but the Disco breech is alright also.

THese carbines are alot of fun, but with the price you  will pay to put it together, you can buy a PRod new and fill to 3000 PSI and have a magazine and a shroud.

[Ribbonstone]

Have to agree...if you want to nrun high pressure, why not get a gun made for it?

BAM50/51's are about gone now...but were selling for under $300 for a time, and I saw a used on (with a decent scope) for $220 this week (on another forum's classifieds).

Pneumas are selling for less than $300 new (and one poster mentioned them at $269 at once site). Seems like shooting fast is not a problem for these (most owners are figuring out ways to make them shoot slower).

That's about it for PCP's close to the Discovery price range.

[rsterne]

the Disco tube has been tested at over 7000 PSI.

Was that a one time test, or did it include fatigue cycles?.... MSWP (maximum safe working pressure) for pressure vessels under 2" in diameter (which don't require hydrostatic testing) are in general engineered for a 4:1 safety factor.... This is done to allow for misuse, fatigue, and even a small amount of corrosion.... While I would agree that 3:1 is probably good enough if you periodically inspect the tubing for corrosion, I wouldn't dream of going down to a 2:1 safety factor or below on any pressure vessel.... That includes the attachments for end plugs, which is basically what the fill fitting and valve are in the Disco....

Several people have done the math, and the limiting factor on a Disco should be the screws locating the valve.... The problem is that we don't know what grade they are or what the tensile strength is.... I have seen figures that would predict a shear failure at only 4000 psi, although most calculations seem to be about 6,300 psi.... Crosman's only warning in their instruction manual about overfilling the Disco is that pressures of over 2000 psi will reduce velocity and may cause the valve to lock.... Since they supply a pump that is capable of over 3000 psi I would think they have done their homework.... I personally choose (depending on tune) to fill my Disco to the top of the yellow zone on the gauge (about 2400 psi).... I am not recommending that as safe or that you do the same.... that is completely YOUR decision.... I would NOT, however, fill past that point into the "red zone"....

Bob

[roachcreek]

I used to have the specs on those screws, and I even have some around here somewhere on a project I was working on.

2240's with their roll imprints are taken to 3000PSI on a daily occurance, no one I am aware of had had to have their next of kin scrape gray matter off the scrapnel from one, but still it makes some nervous.

I started off filling mine to 3000 PSI when I still had the 2240 tube, but I was also using a Hipac system, which by the way is where I got the spring to work my hammer and valve at 3000 PSI.  Everyone said that would be a handgrenade, but they are still in service, even thos some forums would not even allow the name in print.

I no longer have a Disco, and have no plans on ever getting another, but it was fun, I pushed the envelope, if you do and the stars are not aligned it may well be your next of kin that have that clean up to do.

I sold that gun to get one that I have now, and it fills to 4500 PSI.

But it is just me,  I just like to travel the wild side of life.

[lloyd-ss]

  NOTE - THESE ARE EXAMPLES AND ESTIMATES ONLY.   DO NOT EXCEED THE MANUFACTURERS RECOMMENDATIONS WHEN FILLING ANY TANKS.
 RECOMMENDED SAFETY FACTORS VARY FROM 2 TO 1 UP TO 5 TO 1 AND GREATER, DEPENDING ON THE MATERIAL AND APPLICATION.

This is just an example showing some of the calculations that must be done before even thinking about undertaking such projects.  The manufacturers deliver safe products, but modifying them can very easily throw all that safety away.

 .75 tube I.D. = .442 sqin x 2000 psi = 884 pounds of force on the end of the valve assembly.

qty (3)  8-32 screws at .014 sqin each x 75ksi tensile(THIS IS AN ESTIMATE ONLY) x 60% derating for shear
    3 x .0145 x 75,000 = 3262 pounds x .60 for single shear = 1,975 pounds of shear strength
    provided by the screws.  Since the load at 2000 psi is 884 lbs, the safety factor is approx 2.2

The tank is .875 O.D. x .062 wall at 40ksi yield(THIS IS AN ESTIMATE ONLY) / 3 safety factor = 2,750 psi maximum working pressure if the tubing is in perfect condition.

Based on the above, as has been said by others before me, the 3 screws that hold the valve in the tube might be one of the first things to let go if the tank were abusively overfilled.
 
DO NOT EXCEED THE MANUFACTURERS RECOMMENDATIONS WHEN FILLING ANY TANKS.
(edited to add more info and warnings)

[rsterne]

2240's with their roll imprints are taken to 3000PSI on a daily occurance

This, IMO, is a very dangerous practice.... I have seen roll-stamps that were so deep the inside of the tube was distorted.... In addition, we have NO idea what Crosman make the tube from.... When people talk about converting a 22XX to HPA I always recommend that they protect the gun with a 1.8K burst disc.... For additional peace of mind, it is also a good idea to make sure that the roll-stamped area is not pressurized.... by using an extended valve front end.... 

HPA IS DANGEROUS - IF YOU DON'T KNOW WHAT YOU'RE DOING - DON'T

Bob

[lloyd-ss]

............................
I cant seem to find out how to calculate how many fills I can get out of a 90ci 4500psi paintball tank. So far all the calculators are in cubic feet.

.................................

Look at the top of the page of  the GTA Library.  The fill calculator there has a table with the conversions for paintball tanks.
Lloyd

[justkillurself85]

So I looked into it and a Guppy tank is equal to 110ci so that 90ci tank would only give me about 8-9 fills. Still cheaper though.

The whole reason I was thinking about building one from scratch is because it would probably be cheaper considering that I would scrap a lot of the stock stuff from one that I would purchase.

Also the reason I asked if it could be taken above 2000psi (ex. 3000psi) is if later on I wanted to get a little more power out of it. At that time I would drop the money to get a SCBA tank. I dont think that gonna happen now from what you guys have mentioned.

I could just buy a better gun for what I would spend piecing a disco together, but at the same time if I start modding it then I'm getting deeper in the hole with it, and I have to drop more money up front for the fill tank/s for it.

I'm still trying to decide which way I should go with this. I pretty sure its either gonna be building a .22 Disco or goin straight to a .25 Mrod.