I use this spring: 9637K26 (McMaster part #).
Its a beast. Its more powerful than the AR-15 spring. You get 5 for $10. Each spring is 11" long.

YOu were not kidding that it's a beast! ! You said you used this in a Long Shot? I"m modifying a Recon CS-6 and i'm making some of my own "new" modfications to it, but taking the idea from DeceitfulSteve who used an AR-15 Spring for his mod of the Recon CS-6 (see: Adding Another Spring To The Recon, And a reason to use the stock)

I'm wondering if now I should use the AR-15 Spring (need to buy one if so) instead of the one quoted above. I'm concerned because I need to compress it by 5.5" instad of the original 3.25" as it is now. I'm expanding the air resevior and so the orange piece (what I call the Breach Block) will slide back 5.5" instead of the 3.25", so the spring needs to expand by 5.5". The 11" spring is plenty long, but will it compress enough without breaking any plastic pieces

Thanks

ShadowTank

What is the wire size of the AR-15 Spring you are using for this Mod? I'm moding a Recon slightly different and I purchased a spring: #9637K26 from McMaster part, from another thread (Spring Criteria?) and this spring seems very stiff to do the job. I'm wondering if I should buy an AR-15 Spring instead of what I bought.

OR should I try finding a "lighter" spring. With the modification I am doing, I am increasing the distance the "breech block" (or what I am calling the breach block, the orange internal piece that slides back and forth) slides back, thereby increasing the amount of air in the chamber (which I am also replacing) so instead of the original 3.25" it slides back, it will slide back a total of about 5.5". So the spring needs to expand to push it forward that distance. I'm debating if the Spring I have now, or even an AR-15 Spring will be too difficult to compress that much and if I should try finding a smaller dia. wire size spring.

Does anyone know of a spring that would be say 6 or 7" when fully expanded to push a distance of 5.5" after being in its' compressed position?

Thanks very much!

ShadowTank.

>>>>Even with an angel breach you're not going to get darts to vacuum load.

I'm not looking to use the Vacuum to load the darts. I'm concerned about a vacuum forming in the barrel while it is being fired if the volume of air needed to push it out of hte barrel is less than the supply of air being provided by he plunger, thereby possibly reducing the effective range of the weapon. Tho by increasing the size of the bladder/plunger, I hope to elimiate this possible problem, but i'm not sure how well that is going to work so i'm trying to plan for all options here.

Nice paint job BTW on that CS-6 Recon!

You do not want to put anything in the faux barrel attachement. It does not seal with the bolt and so anything in it will only contribut to the friction acting on the dart, not the barrel length.

I intend on modifying the bolt so that there is a tight seal (including the use of O Rings) between the bolt and the new liner of the barrel. Also, with the introduction of a inner tube inside the existing one that is the bolt, I will be able to actually extend the length of the bolt, thereby being able to increase the size of the air bladder so that there is even more air available to force the dart out of the barrel, hopefully increasing range. I know it's a "long shot" but i think worth the attempt! I will report on it's progress when there is some. Right now I need to order cutting bits for a laythe to turn down a piece of PVC pipe.

>>>If you mean the barrel accessory, it isn't really a barrel. It is a worthless tube that if anything decreases the range because the dart bounces against the sides.

That is why I am inserting the CPVC pipe so that it acts more like a barrel, hence the reason why I am asking about air volume.

>>>You don't need to deal with a vacuum in the plunger tube until you have a good seal with the plunger head and some other parts. This doesn't happen in recons unless you made an angel breach and sealed it all up.

That's the plan. The piece that slides back and forth (I will call it the bolt - but if i should call it something else please correct me. I've been moding nerf guns for years, but never learned the proper terminology of the various parts of the gun) instead of the dart being seated in that tube that slides, I am filling that tube so that as you slide the bolt forward it pushes the dart forward into the "new" barrel. Not sure how well it will work, but if successful, i wil ltry to post it here.

>>>The ideal barrel legnth depends on more than the volume of air going through it. I think boltsniper made a guide, but I haven't seen it.

I thought I saw something concernign this in the past somewhere, but I can't find it! *sigh* IF anyone has a link to it, I would greatly apprecaite it. I will continue try finding it using the search engine but i'm lousy at using it. Maybe i am putting in too many criteria to search. Oh well.


>>>I don't know how this looks like any blaster used by stormtroopers. It looks nothing like the BlasTech E-11 which is the most common. Maybe the DLT-20A but that is quite a stretch.

You are correct, up close it doesn't look anything like it. But from say 20-30' away it sort of does. OK, I admit, it's a stretch, i'll admit! guilty as charged! :-X

Maybe I misunderstand the physics involved but if the volume of the barrel is more than the amount of air being pushed through the barrel from the "bladder" when you recock the Nerf CS-6 Recon, then wouldn't there be a vaccum as there is less air than needed to push the dart out of the barrel? Or is that why the barrel is so much wider in dia. than the darts? I just bought a reeming tool to reem out a 1/2" CPVC Pipe so that the standard streamline nerf dart can go down the barrel without restriciton, which basically reduces the dia. of the barrel, but before i do that, i'm concerned a vacuum will actually form, causing the dart to fire a shorter distance than if i leave the barrel alone. Has anyone reduced the barrel length to match the size of the bladder? i like for "form factor" of the CS-6 Recon (it looks similar too a storm trooper rifle once it's painted black!) and I'm modifying the "slider" to recock the main spring so it's located similar to a real shot gun underneath the barrel, so shortenign the barrel will cause problems for that. I've done a search for mods on this gun, and haven't found anything posted thus far that answers this question. There are some excellent mods already posted, and thanks to all who have taken the time to post them. Though I am going to go a slightly different route to modify mine, they have given me excellent ideas!! Any thoughts? Thanks!!

ShadowTank

True, but each thread deals with a specific issue/topic.

I belong to several different discssion groups/forums, and this is how threads on those places are done. I am sorry if things are different here and I have upset the apple cart.

Shadow Tank.

Couldn't this question be posted on your RF20 thread?
Maybe it's just me, but starting a new thread for each individual question seems kind of unnecessary.

Totally. This guy has around 5 threads all with various RF20 questions.

Thanks Captain!

The opening is only 1/8" in length (the thickness of the "restrictor plate".

Do you think not being in the center of the barrell hole will matter either?

Shadow Tank

Narrower opening restrict the flow rate, but the amount of the restriction depends highly on the length. It's best to not narrow any passages below 5/32" for very long or you will lose performance. Reducing to 1/8" only once should be fine.

I am making a a new turret/barrel assembly for what I'm calling the ST-3. I am using the Nerf Rapid Fire 20 as a guide for it. For the RF-20, the opening from the piston to barrel is about .25" in diameter. Because of certain design issues I may need to reduce that opening to .125" in dia, and maybe even .094" in dia. FOr the .125" dia to work, the hole between the piston and the barrel would be off center. So my questions are this.

What issues can I expect by reducing the hole in the first place?

Would it matter if the hole is "off center" or not?

Just as a reminder, Pressure is constant/consistent using CO2 with a Low Pressure Regulator since pressure is a factor.


Thanks!

Shadow Tank

I know if I have the CO2 low-pressure regulator cranked all the way, my RF-20 will fire all 20 rounds in under a second. I was just curious what the original RF-20 specs were.

Shadow Tank.

I don't anymore, but I think I could get all 20 out in under a second.

The reason is, with the CO2, and such a high rate of fire, I empty the mag in less than 2 seconds. Even with the "quick change" mod I did (a mod design by Falcon, I believe, except I super glued the gray piece of the gun frame to each turret, and I hold it in place with rubber bands - as shown, vs what he did which was make it a "flap" attached to the actual gun), and having spare turrets/barrel mags, it was not enough. I am still getting killed. If I was more mobile than it would be sufficient. But I can't move very fast at all, even to walk can be difficult with being fatigued and tired due to health reasons. So, I need to develop a gun with more firepower. The ST-3, the current RP20 Mod I'm not sure if I should even call it a mod. It's more I'm using several parts from the RP20 to make the ST-3.

Here are some current "sketches/plans" for the current design.











As of tonight, I have tested without being in any frame, firing two pistons from one (CO2) source, and it worked!

I have also modified the RP20 Gun frameto the size I need. Basically I chopped off the top pieces along the top edge where the top of the Bladder used to be and on the front so it is one "smooth" surface to mount to the steel plate that you see in the first drawing.

My biggest stumbling block is to find someone who has access to a CNC Mill to make the plates for the drum. To have it done at a business will cost several hundred dollars, which is a bit over my budget. This thing has already cost over $100 in parts, but when it is all together, it will be well worth the effort. :-D


Shadow Tank

Lookin' good, bro.

<SNIP>

But why you'd want to do the "double" tank is beyond me....with that rig you've got, you be throwin' some serious dart down the way. But....I can see that you have the ability to challenge yourself with such a mechanically complex monster. Good luck, dude.


-Piney-

Would anyone have any idea what is the maximum air pressure (measured in PSI) that the Rapid Fire 20 would have when the pressure is released from the air bladder ?

Shadow Tank

I am asking questions concerning the mechanics of the Rapid Fire 20, not how to convert a nerf gun to CO2. I only mentioned i'm using CO2 because the pressure will be higher than when using tradtional "Hand-pumped" pressure which would most likely not be sufficient to supply air to two cylinders/pistons.

Since this Forum discusses several different kind of mods that are possible with nerf guns, I was presuming that someone would have an answer to my specific question concerning using two cylinders/pistons at the same time and what speciofic complications might there be.

One person already replied indicating they tried it, but the issue they described I'm not sure how that would occur and I asked for clarification.

I was only asking a specific mechanical quesiotn about the RP20, not about how should I go about to making all of the modications needed to accomplish the goal. I realize I am in unchartered territory here, so there is going to be risk, and much trial and error that I will have to do on my own. Especially when it comes to using CO2.

I did not and do not intend or mean to insult or otherwise proclaim anyone being wrong in terms of what they have said, including warnings about using particular materials (such as CO2) I only speak from what I have experienced and as long as you upgrade critical parts, including the air lines, i have found Nerf Guns can be upgraded to CO2 successfully, but that isn't the purpose for me coming on here and asking the questoins I have. I have observed for myself the mechanical operation of an unmodified Rapid Fire 20, and I believe my understanding on how they work is correct, however, I always found it is better to ask others who also may have knowledge on how they work to confirm or not that understanding.

And here are two pics, one assembled, the other showing the internal parts for the successful ST-2 that I have been using for over 4 years.







Enjoy!

Shadow Tank

If you have been successful with CO2 in your Nerf blasters for 4 years, I don't understand why you're coming to a forum where most of us don't even bother with CO2 in our blasters.


CaptainSlug, who by PROOF and WORKING EXAMPLES is probably one of our best authorities on compressed gases, lent his opinion, "too complicated". If that doesn't work for you, go and rattle on, but most of us won't be overly concerned (except maybe the newbies who will be impressed by the technological theory and concepts and stuff.)


There's a saying that goes around discussion forums. This thread is worthless without pictures.

If you have that much experience and advanced knowledge of a CO2 powered, fully automatic, high capacity Nerf blaster, you certainly must have a digital camera somewhere.




I'm wondering why I'm coming to the forums less and less now.

Sorry, Nerf Rapid Fire 20

Shadow Tank

What gun?

I have been using CO2 for 4 years now, with great success now, though in the beginning there were problems. You are correct about Plastics not liking CO2. During the first 3 years of use, I had constant problems with the plastic line from the CO2 pressure regulator I was using to the trigger/valve assembly cracking and bursting. I then looked into why this was happening and discovered the CO2/Plastic issue, and replaced the line from the regulator to the trigger/valve with Steel lines. I use a 20oz Tank with a hose line. By the time it reaches the Trigger/valve it appears to have "expanded" enough, because since replacing the line as I described, I have had no issues whatsoever.

I do apprecaite the valid concerns and warnings, and they are appreciated. However, by shear experience, I have now able to overcome these issues, and it performs with excellene.

ShadowTank

There is a reason I am called ShadowTank. With the group I belong to who I particpate in Tactical action with, my character is a Weapons Design & Bulider Specialist. People love to play with me and my advanced weapons, cuz, at some point, I do run out of ammo, and usually get killed while reloading, it is the one downside to such a weapon.

Although my weapons are advanced, my health is not. I can not run, or even walk faat without having heart/breathing problems. So I am semi-stationary most of the time. So my "targets" can quickly move and get out of range if they see me before I fire. So this weapon "levels" the playing field for me.

I have a modified RP20 using the standard Turret/Barrels, using a mod I found online that allows you to interchange turret/barrels. I have 4 spare ones plus the one mounted on the Gun, and it is not enough. It still has it's deficiencies.

I also modified it for CO2, and was told in the past it would be too complicated, but I was successful at it. I'm just trying to get as much information as possible from those who might have tried something like this, or knows how these guns work mechanically to get more input and to determine if my understanding of the mechanics are correct.


I have managed to design, thus far, a way to mount the two cylinders on top of one another. I discovered there are holes int he back of the piston/cylinder assembly so there is no vaccum created for the space behind the o-ring in the middle of the assembly. I can trim/cut the cylinder in the back to make it 1" in dia, so the spacing for the holes in the Turret/Barrel assmembly will line up to a .5" spacing for all 4 barrels.

Does anyone have any thoughts on the possible "backflow" issue with the co2 firing into the turret/barrel assembly with no open holes? Is the very tiny space between the turret and cylinder/piston enough for the CO2 to escape without pushing the piston back causing damage?

OR, is it possible, that it won't effect it, it might stay "in" the forward chamber if it can't all "Escappe" and by the time it is about to fire, the turret/barrel will be "open" and start to fire?

Any information that can be provided would be greatly appreciated.

ShadowTank

Using a simple CAD program, I have already calculated the necessary angle for each barrel, as well as a different type of advancing mechanism. I am using the piston to go back and forth, but the method of advancing the barrel/turret is differnt than the original design.

After posting this, I later on realized that it doesn't matter how fast or slow the piston rate is. What is important is the teeth are aligned properly so when the piston advances the turret to the next position the hole lines up with the piston/cylinder when the CO2 is released.


Because of the tight spacing between the teeth on the turret, I do not need to use a lever/spring assembly for the advancing arm. I am usign a straight single piece that will advance the turret. It is difficult to explain in words how it will work. If I have the free time, which i don't right now, I will scan a copy of the sketch I have for the design of this arm to show how I plan on doing it.

RIght now, my larger consern is as each time it "fires" both cylinders will be pressurized. When they release, there is no place for the CO2 to go with one of the cylinder's. THe issue of backflow and causing damage to the piston/cylinder assembly is one I don't know if it would happen. or, since there is some space, no matter how small, it is not a perfoect seal between the cylinder/piston assembly and the turret, so the CO2 does have a place to displace, though not through the turret.

BTW, when I first looked into using CO2, I was told it could not be done and I should abandon the project. Well, I went ahead anyways, and through many tirals and errors, it did eventually work. The same is most likely going to be the case here too.

ShadowTank

The reason I am asking, is I am doing a Major Mod to this, by possibly making my own "Ammo Clip" that will be a larger radius to hold more nerf darts. However, to make it work, i need to change the "rate of fire" or maybe better explained, the timing of the advancing mechanism. Understanding how it works would enable me to possibly modify it without destroying it. ANy thoughts?

You have to change the degrees of rotation that each piston cycle rotates the turret. And you obviously have no idea how hard it is to design such a change. You would have to make your own ratcheting clutch as well.
My expert opinion is: to forget it.

I don't understand how that could happen.

What i'm talking about is the cylinder that advances the barrel/turret and releases the air into the barrel chamber once it has advanced the barrel/turrent to the next position. I want to stack one on top of the other, so I can have 4 rows instead of the two that now exist. The design of the barrels/turret would be similar to the original design, only bigger. THe darts would be in the barrell just like the original RP 20.

ShadowTank

Yeah. I tried that. But I had a piston pushing darts back into the turret. It REALLY complicated. Be warned.

Yeah. What i'm conceiving is basically a "Tommy Gun" Design. The other issue I am trying to work out in the design is how to attach a "beam" of some kind accross the top, to extend past the barrell/turrent assembly so I can add a front support for the barrell/turret assemblyt AND a front handle, and a barrell to place infront of the assembly.

Shadow Tank

Wow thats fairly well thought out for just a concept thread... Hope it work, because then it would be the first homemade automatic... or well... you get my point, and its 10:00 and I cant think.

Does there need to be a seal behind the middle O-Rings so that the part of the cylinder where the main spring is needs to be sealed? Or Can I cut into the clear plastic as long as the area in front of the Orings in the middle of cylinder is sealed am I ok?

THanks

Shadow Tank

The new version of the Modified RP 20 I am working on, I plan to have 4 circular rows of darts, fired by two air cylinders. Only one will advance the actual ammo clip. I am using CO2 so I have plenty of pressure to supply both. I have had great success using CO2 with what I call the ST-2 which is the RP20 modified to use CO2.

I am custom making the ammo clip. My question is, if I wanted only one row to fire at a time, I would have to have the barrels in the ammo clip offset by 1/4 instead of 1/2 a barrel. Which means when one of the cylinders fire, they would be firing into an obstruction. Would this cause the cylinder to become damaged becaue the CO2 has no where to go. the only other option I can think of is not to use the cyliner, and just run a line to the other two holes and when pressure is released by the trigger, it will flow and where there is an opening for the barrel, it will release the CO2. Sure there will be some leakage, but only when I'm firing.

Any thoughts other than I'm nuts for doing this?

Shadow Tank

Is there some kind of pressure release valve, that it reaches a certain point, and the air pressure "escapes" causing the assembly to recoil back?

That's pretty much it. It's a combination and an air cylinder and a regulator. The compression rate of the spring set the pressure level at which the piston actuates. And once it reaches the most forward position it gets past an o-ring and the pressurized volume of air escapes. This simultaneously fires the dart and allows the spring to push the piston back to it's starting position.

Any idea on what is the distance it goes before returning to it's original position? I'm having a difficult time figuring that out.

Thanks!

Shadow Tank

The reason I am asking, is I am doing a Major Mod to this, by possibly making my own "Ammo Clip" that will be a larger radius to hold more nerf darts. However, to make it work, i need to change the "rate of fire" or maybe better explained, the timing of the advancing mechanism. Understanding how it works would enable me to possibly modify it without destroying it. ANy thoughts?

Shadow Tank

I'm trying to do some differnt "new" mods that have never been done before, but before I do so, I'm trying to figure one thing out which may have an impact on the design of the mod.

How does the Rapid Fire 20 recoil work? THat is, what causes it to spring back once air is released by the trigger? it pushes forward, then recoil backs because of the spring? Is there some kind of pressure release valve, that it reaches a certain point, and the air pressure "escapes" causing the assembly to recoil back? I don't want to have to take it apart because I fear it will no longer work if I do, but i'm hoping someone has figured this out, or knows, perhaps by discecting one that no longer worked?

Thanks!

Shadow Tank