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rsterne · Moderator

Before I start, please read the following safety warning. If you want to pressurize the main tube in a Crosman 22XX, you MUST consider the following. Crosman never designed the tube to hold pressure, except in the case of the Benjamin/Crosman Discovery. Most of the Crosman main tubes have a "roll-stamp" where the model number and safety warnings are pressed into the tube and weaken it. I have seen various versions, but most 2250s I have seen have the roll-stamp behind the front trigger screw, whereas most 2240s and 2260s have a longer roll-stamp. This area should NOT be pressized as there is the danger that the roll-stamp will act like the "pineappling" on a grenade. In extreme temperatures (or even at normal temperature if overfilled) with CO2, pressures may reach 1900 psi. Available engineering data and information about similar tubing suggests (but does not guarantee) that you should NEVER exceed 2000 psi and prudence therefore dictates that any bulk-fill CO2 or regulated HPA conversion should be protected by the use of a 1.8K burst disc. Since these discs are rated plus or minus 200 psi, that means they will burst at between 1600 and 2000 psi. In practical terms, because of tolerances, this limits the regulator pressure to a maximum of 1400-1500 psi. If you are pumping with a hand pump, you have more control over the results, but I personally never use over 2000 psi, and then only if the pressure is restricted to the area in front of the roll stamp. In addition, once you pressurize the main tube, the valve (and whatever plugs the front end of the tube) are subject to an end force of nearly 900 lbs. at 2000 psi. The stock 22XX valve is retained by a single 6-40 screw which will NOT take this pressure without failing. The Disco valve is retained by three 8-32 screws screwed flush to the valve body with the heads located in 5/16" holes in the main tube. This would appear to be the MINIMUM acceptable strength for locating the valve at 2000 psi. If you pressurize the main tube, you do so at your own risk, and you MUST takes steps to properly locate the valve and ensure the safety of the end plug.

I just thought I would share some of my findings regarding various valves for use in 22XX HPA conversions.... I have experimented with quite a few configurations and come to the following conclusions:

Crosman 22XX Valve

With 22XX Front End

The simplest way to convert to bulk CO2 or HPA is to use a "dummy powerlet" held in place by the Crosman end cap. These typically are made from aluminum, with a thick wall, and tapped 1/8" NPT on the bottom (some also on the front) for a remote line. The advantages of this arrangement are many:

The only modification necessary to the gun is drilling a hole in the bottom (or side) of the main tube for the remote line.
Only the valve and powerlet are pressurized, not the main tube, so the stock 6-40 screw retaining the valve will work fine.
You can go back to using a powerlet simply by removing the dummy powerlet and replacing it with a 12 gr. CO2 powerlet.
For increased flow, you can remove the piercing pin inside the valve, but then it won't work with a CO2 powerlet any more.

A similar arrangement can be obtained by drilling and tapping the front end of the valve to 1/8" NPT to directly accept a remote line. You would also remove the piercing pin, and you may have to make a tubular spacer to act as the front spring seat inside the valve if you drill right through before tapping. Alternately, you could fit a longer valve spring. Since only the valve is pressurized, it doesn't need extra locating screws.

Muzzle Mack Extended 22XX Front End with O-rings

In collaboration with me, Joe at Muzzle Mack Products, has developed an extended front end for 22XX guns designed to address the safety issue caused by the roll-stamp. The O-rings are far enough ahead to restrict the pressurized area to be ahead of the roll-stamp on a 2260 tube (the other roll-stamps are shorter). The forward portion of this front end is drilled out to increase airflow and help make up for the slight loss in volume created by the longer valve. You would remove the piercing pin when using this front end. You could also use this front end on the B&A Boss Valve (or Disco) back ends if you are using a tube with a long roll-stamp such as the 2260. You need to properly locate the valve in the main tube to withstand the end force.

Bryan and Associates Valves

B&A makes three valves which can be used in 22XX PCP conversions.... They have different features as follows:

Economy Bulk-Fill Valve

This valve is desigined to be used on bulk-fill CO2 guns and consists of a new front end with O-rings to seal the valve to the outer tube. It uses a stock 22XX back end with the only internal modification being removal of the piercing pin. This front end is too short to cover the roll-stamp on a 2260 and most 2240s. You need to properly locate the valve in the main tube to withstand the end force.

Boss Valve

This valve is designed to increase performance in a 22XX by increasing the flow of CO2. It has a reputation of increasing performance at the expense of fewer shots per powerlet. It has a modified back end featuring the following differences from a 22XX valve:

Increased internal volume achieved by shortening the threads, boring the ID to about 5/8", and moving the valve seat back 0.060"
Angled exhaust port and increased ID exhaust valve seat

Since this valve has no O-rings to seal the front end to the main tube, it can only be used for bulk-fill or HPA by drilling and tapping the front end for a remote line or using a "dummy powerlet" style conversion. In addition, it still has the piercing pin in place, which would normally be removed for these applications.

Boss Max-Flow Valve

This valve was designed to be used on bulk-filled CO2 guns, and has a reputation of producing great power but with high CO2 consumption. It combines the above two configurations, plus has a tapered front end to further increase CO2 flow. This front end is too short to cover the roll-stamp on a 2260 and most 2240s. It has no piercing pin and a shortened exhaust valve spring guide. You need to properly locate the valve in the main tube to withstand the end force.

Both the Boss Valves have the exhaust valve seat moved back 0.060", which for CO2 use allows more valve opening and CO2 flow. At the higher pressures typical in HPA applications, this modification actually may work against you, as the hammer now has less travel in which to build up momentum. It will therefore not open the valve as far at those higher pressures. In order to get back the same hammer strike, you will need to shorten the valve stem by that same 0.060".

It should be noted that ALL of the above valves (Crosman and B&A) retain the standard 22XX Crosman exhaust valve poppet configuration using a brass head with a relatively soft insert designed for CO2 use. In practice, this does not work well with PCP pressures, and will likely have to be replaced with a different exhaust valve poppet such as that used in the Disco.

Mountain Air 22XX Bulk-Fill Valve

I have not seen or used one of these, but from the limited information on their website, it would appear to be similar to the B&A Economy Bulk-Fill valve. There is no mention of internal modifications. This valve has an extended front end, but it would not be long enough to cover the roll-stamp on a 2260 and most 2240s. There do not appear to be any additional mounting holes, so you would have to locate the valve properly to withstand the end force. There is an option, however, of a Delrin valve stem, which would likely be much better in HPA applications, although I have not had the opportunity to try one of theirs. This valve stem is also available separately.

Discovery Valve

This is the valve with which I am the most familiar. It is made from aluminum instead of brass, and is dimensionally identical inside to a 22XX valve, but it is designed from the ground up for HPA (actually dual fuel) use. It has a hard plastic valve head, molded over a steel stem designed to withstand HPA pressures. The stem is sealed at the rear by an O-ring, something none of the other valves have. The front end is extended and sealed to the main tube by two O-rings, although it is not long enough to cover the roll-stamp on a 2260 or most 2240s. The hole through the front end is 1/4", putting it between the one in a B&A Economy and Max-Flow valve. The back end is drilled and tapped for three 8-32 screws to locate it into the main tube, again something none of the other valves have. When installed in most 22XX tubes, the extended back end of the valve where the stem O-ring lives will interfere with the tiny 4-48 breech screw. This can be cured by carefully grinding a notch in the top rear of the valve with a Dremel to clear that screw. IMO, it is the simplest (and cheapest) way to achieve an HPA conversion of a 22XX, provided the O-rings are ahead of the roll-stamp on the main tube you are using. If they aren't, you should use the extended front end offered by Muzzle Mack or make one yourself.

I hope that this article will enlighten you as to the differences and characteristics of the various valves. Please feel free to ask questions and I'll try to help. Remember, any HPA conversion has dangers, and you undertake them at your own risk. STAY SAFE !!!

Bob

kanyon · Silver Status Member

Very interesting.....

So just build a whole new main tube.. Cool

in stainless would look great.....
bore it from both ends leaving a shoulder for
the valve to seat against..

Pete

dogon1013 · Member

Or don't pressurize the tube at all. (that's my plan). that way you have less seals to worry about leaking too.

If Muzzlemack would just make that extension a little longer, and thread on a check-valved foster fitting. I'd buy one....Hint Hint

rsterne · Moderator

If you don't want to pressurize the tube, the simplest way is to just drill out the front of a 22XX valve and tap it 1/8" NPT.... then fill it directly from a remote tank and line.... Cool

Making the extension longer would severly limit the number of shots if you are only filling the extension.... and why else would you need a foster fitting on the front?.... Neutral

Bob

dogon1013 · Member

for a remotely mounted tank. that is removable, if you want. (I like options)

it would effectivelly have the same capacity as the standard CO2 cartridge, if you fill it with CO2. so the shot limit would be similar to stock.

But then you have the option of hooking up a remote tank with regulated HPA or CO2, if you choose, or just filling the small cartridge size tank after a few shots. The foster fitting is just a nice standard quick connect, and it seems like it would be easy to just add it to the end of the long valve extension that muzzlemack makes (I guess the extension would need to be a little longer).

tapping the valve with the 1/8 Pipe thread works too, but then you have a permanent setup. I like the options of being able to disconnect the tank. This would also allow for having multiple tanks filled, and when one gets too low, just disconnect it and connect a full tank.

rsterne · Moderator

ummmmm.... this thread was about HPA, not CO2....

If you drill & tap the front of the valve, you can go back to stock by replacing the front end.... same thing with an extended front end....

You can have the Foster fitting on the front of a piece of 1/8" pipe screwed into the tapped valve as an extension.... just make sure the pipe is good for the pressure you are running....

Bob

dogon1013 · Member

In your warning you mention how you shouldn't pressureize the tube to avoid grenadeing it, so I proposed another option.

I wasn't trying to steer this thread away from HPA and toward CO2. If the valve and whatever add-ons you use can handle the pressure of HPA, it can certainly handle CO2, so the ability to go back and forth is another nice option. A quick connect fitting would just make it very easy too switch between them, instead of having to get the wrenches out....and re-do the plumbing.

You don't have to choose between CO2 and HPA...You can have both in one setup. That's what I'm getting at.

rsterne · Moderator

The intention of my original post was to give information about the various valves available to convert a 22XX to HPA.... There are lots of other ways to do this.... some of them will work with CO2, some not, no argument there.... I don't want to get into a long winded debate with you about what can and can't be done, and the merits of each.... You are perfectly welcome to come up with your own ideas, do the work, and post the results.... that's what I did, nothing more....

My personal opinion is that using an extended valve front end (only) as an HPA setup would give you a very limited shot count.... I'm sure that it could be made to work fine on CO2.... and I'm also sure that there are tons of ways to connect a remote CO2 or HPA bottle to a 22XX.... some of them safe and some not so safe....

As to my safety warning.... I didn't say NOT to pressurize the tube.... I just gave my opinion about the safety issues (eg roll-stamp) and how to work around them in a logical manner.... There are other ways to convert a 22XX to HPA, including building a completely new main tube from better material, starting with a Disco main tube, and others.... This thread was about how to use Commercially Available valves to do the job and the pros and cons of each (in my opinion).... It was aimed at people who have reasonable skills and intelligence who are interested in converting a 22XX to HPA but don't have access to a full machine shop and/or the engineering skills to analyze a design as to workability and safety....

If you wish to continue expounding on the ideas of utilizing a custom made valve extension or other custom parts or ideas, I respectfully request you start another thread on that.... Wink

Bob

Jaxom · Senior Member

Bob,

To the best of your knowledge, do you know if anybody makes replacement tubes that aren't rolled? I like the size of my 2300 as is. Although it's my intentions to be using Joe's bulk system on it, so that may not matter anyways.

Thanks for the explaination on the various different valves out there. I think I may be adding a disco valve to my parts list for my 2300. To bad there isn't a how-to/sticky with pictures on how to do this...(hint hint).

Jax

rsterne · Moderator

Jax....

I haven't seen a tube on a 2300.... where does the roll-stamp end relative to the front trigger screw hole?.... I can't imagine it's further forward than on a 2260, and Joe's valve extension works for that.... If it's like a 2250, then any of the valves I mentioned (with O-rings) will work....

Bob

Jaxom · Senior Member

Now I'm starting to wonder what you mean by roll stamp. I've seen powder burners with a hard serial stamp in them. All the lettering and numbers on the tube on the 2300, left side, right side and bottom all seem to be painted on. Running my finger nail across, all this seems smooth to me.

I'd like to pull ever bit I can out of my 2300 that I can. If I understood all this pairing a disco valve with joe's bulk will help me achieve this.

I have a few more questions about my mod, but I don't want to jack the thread, which imho should be a sticky!.

Jax

rsterne · Moderator

Jax....

If the numbers on a 2300 are painted on, like a Disco.... rather than stamped into the metal (like on a 2240/60).... then you don't need the extended front end.... It's main purpose was to move the pressurized area ahead of the roll-stamp on a 2260.... Wink

If you are going to stay with CO2, my guess is that the B&A Boss Max-Flow Valve is your best bet for sheer power (it's bigger inside than the Disco valve).... I understand that the shot count may drop to about 17 per powerlet, so you will want to bulk it.... You will have to drill the 2300 tube and fasten the valve into the gun for safety once you pressurize the main tube.... You could use a B&A, Mountain Air, or Disco bulk-fill fitting on the front.... Mr. Green

If you want to convert to HPA, then I would use a Disco valve.... It's already got the mounting screw holes and an over-molded valve stem designed for HPA.... all you need to do is drill the 2300 tube for the mounting screws.... I would use a tank regulated to 1400-1500 psi output and equipped with a 1.8K burst disc.... and a Rear Velocity Adjuster of course with a Disco hammer spring.... If you only fill the tube, you will get VERY limited shot count, but if you use Foster Fittings you could use it either that way or with a remote tank.... Cool

I don't know what barrel length you are using, but I got the following results with 14.3 gr. pellets:
14" barrel, stock Disco valve & TP, 1400 psi, no RVA: 750 fps
24" barrel, ported valve & TP, 1400 psi, RVA at medium: 880 fps
24" barrel, bored out valve, 1600 psi, stronger hammer spring: 990 fps

With a 24" barrel, stock volume Disco valve with the corner cleaned up, drilled transfer & barrel ports (or poly port), running a 13 cu.in. tank regulated to 1400 psi, with an RVA using a Disco hammer spring, you should be able to adjust the gun from about 250 shots at 500 fps up to 50 shots at 900 fps with 14.3 gr. pellets.... YMMV of course.... Twisted Evil

Bob

Jaxom · Senior Member

Ah, I think that's it then. I'd of taken a picture but I don't think it would show very well. But if you are indeed saying that the stamp would leave an indentation for each letter/number. Then this is indeed painted on.

As I stated in the rifle section, I'm going to be using joe's bulk kit, I don't see how I can add a power adjuster in then.

Two questions... You wouldn't happen to know of a link showing the step by step process with pictures on how to swap out the stock vavle for a disco one, and what tools/parts besides the valve, to do so.

Second question. While I have some money in order to pay for this mod, I don't want to go hog wild, what money I do have from my mother's estate has to go towards keeping me in the house. Having said that, I may hold off until I find work before ordering the disco with a pump. If I filled one of the paintball tanks with C02, just to test the pistol, once it's empty, can I refill it with air using the disco pump?

Thanks,

Jax

rsterne · Moderator

The Disco valve is a drop in except for one very important thing.... You need to drill three 5/16" holes at 90 degrees to each other (and to the transfer port) in the main tube at the transfer port location (and carefully deburr them).... When you get the Disco valve, get three of the mounting screws as well (they have a 5/16" D. pan head).... This needs to be done accurately, as you want the heads to be a good fit in the holes.... otherwise the shear load (nearly 900 lbs) will not be equally distributed on the three screws.... Rolling Eyes

I'm not sure where the hole is for your 4-48 breech screw.... If it is ahead of the bolt when open you will also need to Dremel a recess in the top rear of the Disco valve to miss the screw.... If it is covered by the bolt (like a Disco) then you won't as the valve will be ahead of the screw.... Cool

Once you mount the CO2 tank on Joe's rear HPA adapter, you can pressurize it with the Disco pump.... You will need a male Foster fitting with check valve screwed into Joe's adapter, and you will have to leave the tank on the gun while filling (and don't try and remove it unless the pressure is under 800 psi).... You will also want to mount a gauge somewhere, I would suggest one from a Disco.... The CO2 tank is rated at 1800 psi maximum, but if you pump it to that you MAY burst the 1.8K disc on Joe's adapter.... Your other alternative is to get a 3000 psi tank/regulator combination and I would recommend you stick to a regulator pressure of 1400-1500 psi so you don't burst the disc.... The regulated setup will give you a virtually flat shot string (no velocity variation) compared to the "bell curve" you will get with just a CO2 tank running HPA.... Rolling Eyes

Using Joe's rear HPA mount, you will need a way to get the HPA from the tank (his adapter) to in front of the valve.... You can do this with "hard" (ie rigid) lines or flexible ones, plus the appropriate elbows, etc.... plus a bulk fitting that threads into the front of the 2300 tube.... You may wish to incorporate an inline valve as well, but make sure it is good for the pressure you are running.... Take a look at the photos on Joe's website, and ask him for details.... Wink

Good luck and stay safe....

Bob

Jaxom · Senior Member

Emailed him direct from his website right after posting on here. Waiting on reply with price quote. I'm quite sure he'll have all the parts I need to complete this project.

I just printed up the discover exploded view and parts list along with the
2300T, which looks nearly identical to my 2300KT. Although I built mine with a 14" long barrel in .22 cal. Perhaps that would help you help me determine where my breech scew is in relation to the valve.