25 replies to this topic

[Dyxlesic]

I apoligize for posting yet another question thread, but I have done research and searched and can't find the answer.
What its gonna be used for:
I'm working on a primary for my brother. He LOVES shotguns. A pump action/semi auto 3-4 shot shotgun with decent range doesn't exist, and it would be extremely difficult to modify a gun to do that (as far as I'm aware). I resorted to a design similar to a couplered pistol, except it would use 1 1/4" PVC with 3-4 3" cpvc/crayola barrels inside. I will use a clippard valve and a _______ tank (backpressure/pin tank) to make it fire a blast of air on every trigger pull (however, the cpvc shell will need to be changed between shots)

Simple English question:
What would be the best air tank to fire a 3-4 round scatterblast with decent range? I would prefer backpressure (ie. salvo, hornet, etc.) But pin tanks (ie. at_k, Titan, etc.) will work too. It needs to be big enough to fire the darts with decent power, but not too big where its wasting air (like a Titan tank would)

Stats:
Loading:1 1/4" couplered
Per shot: 3-4
Barrels: 3" cpvc or crayola

Thanks

Edited by Dyxlesic, 22 February 2011 - 09:13 PM.

[WicketTheModder619]

To get four barrels to go over 50' with a very good spread, use a titan tank. You may have to use a clever trigger though. Depending on his age, a direct trigger may be too much for him to pull back.

[taerKitty]

One of the roto rockets (a Jobar, I think) is backpressure. Fancy way of saying 'hair trigger'. It'll have enough air for him to stuff multiple darts per barrel.

[the mod man]

Cobra's work nicely too. They have a 750M ml tank, but you still need to pump it.

Edited by the mod man, 22 February 2011 - 09:28 PM.

[Dyxlesic]

To get four barrels to go over 50' with a very good spread, use a titan tank. You may have to use a clever trigger though. Depending on his age, a direct trigger may be too much for him to pull back.

He's 13, and a Titan consumes way too much air for this type of project. The air release on a Titan it too slow (as well as Im aware), as I would require longer barrels, which I could not do for this specific design

I plan to make it feed from a bigger air tank, using a "true semi auto" air system, but amo will be reloaded manually. It will use a 3 way clippard button valve (exhaust port covered for a pulpin design).

[princexbuster]

Uhm you could do this with another air tank, but semi-auto shotguns are gay.


This system needs alot of air so anything smaller might not work.

NOOB
\/\/\/

Edited by princexbuster, 22 February 2011 - 10:05 PM.

[ghost recon]

Uhm you could do this with another air tank but semi-auto shotguns are gay.

dont use a pin it is more likely to have a leak it would be easyer to use a salvo or other backpressure tank i have one if you want it

[NerfGeek416]

Jobar would work well.

If you have enough air and parts, it might be possible to have 3 hoppers side by side, for a true semi auto setup.

[princexbuster]

Just make a hamp so this topic can be over.

[Dyxlesic]

I do not know what a rotorocket, a jobar, a hamp, or a cobra are. I checked the modifications directory, and search, and found people talking about them, but I could not find pictures or descriptions. One of them is some toilet cleaner, but idk how it works or anything. As iv said in previous topics, I know plenty about almost every nerf gun, but my hardware knowledge is extremely low

Alright, I looked the my on google.
Jobar: it seems too big, and would use too much air per shot than I would like
Cobra: even bigger than a jobar
Hamp: I don't understand how that could be used here
I was unable to find rotorocket internals or find out how it works

Edited by Dyxlesic, 22 February 2011 - 11:15 PM.

[taerKitty]

Just make a hamp so this topic can be over.

Unsure if it will work for a 'kid brother.' Remember the target audience.

[Dyxlesic]

Just make a hamp so this topic can be over.

Unsure if it will work for a 'kid brother.' Remember the target audience.

Keep in mind this little brother is 13, and is pretty good with nerf guns. I'm looking for an airtank about the size of a marshmallow blaster. (keep in mind the pump is inside the airtank on a marshmallow blaster, which reduces it's volume)
So I did some testing with my Titan tank. The air volume of the tank is so huge, it takes 15 pumps. I want to go with something smaller. How is the volume and air release speed of a bbbb compare to a Titan? I've never used a bbbb

Edited by Dyxlesic, 23 February 2011 - 12:36 AM.

[Draconis]

Just make a hamp so this topic can be over.

Unsure if it will work for a 'kid brother.' Remember the target audience.

Keep in mind this little brother is 13, and is pretty good with nerf guns. I'm looking for an airtank about the size of a marshmallow blaster. (keep in mind the pump is inside the airtank on a marshmallow blaster, which reduces it's volume)
So I did some testing with my Titan tank. The air volume of the tank is so huge, it takes 15 pumps. I want to go with something smaller. How is the volume and air release speed of a bbbb compare to a Titan? I've never used a bbbb

PulseStrike tanks and 4Bs are similar volume to Titans, but have larger dump valves, so they actually perform as well for a lot lower price. The PulseStrike has the added advantage that you don't have to pump it to capacity to still get good range, due to the spring loaded floor. Ultimately, though, the ideal blaster which fits your description is the Big Salvo, which are unfortunately out of production and becoming difficult to locate.

Edited by Draconis, 23 February 2011 - 01:08 PM.

[the mod man]

The new Hydro cannon has a sizable tank that I've been using.

[Boot]

Broken SVT recently very kindly introduced me to the triple strike tank. It is a large backpressure tank, larger than that of a Big Salvo, but smaller than a titan tank (it is rare though)

If you really are going for semi auto you should use a back pressure tank. With a pin tank semi auto setups require multiple processes and valves, while in a setup like the Mirage-SS a single simple valve can be used to efficiently trigger a backpressure tank semi automatically. I also have a (probably doomed) project in the works to create a semi automatic spread cannon. I used the largest backpressure tank I could find, and that is a drain blaster/Cobra/Jobar. To get them to work semi automatically however you have to scrap the stock release valve and attach a suitable semi automatic valve.

Regardless, to get a semi auto shotgun spread you will need a Massive fill tank, anything large enough has to be fitted to a backpack, otherwise I doubt any more than about 3 shots per fill is possible (unless you are using some insane HPA or Paintball tank with a regulator.)

Despite my love for bladders, in this case they are NOT practical unless you make a massive homemade one.

A final possibility could actually be the marshmallow blaster, I'm not too familiar with them, but I think they operate off a backpressure system or something similar. Also there is this off brand BBBB equivalent called the "blast bazooka" (or words to that effect) which has a tank just shy of the BBBB and operates off a backpressure system.

Good luck! I always love outrageous projects like these.

EDIT:

Just thought of something else. Although it wouldn't be semi automatic a large volume springer would do the trick, and if it were pump action, and had a triple inline clip (which I've seen others build, and have tried with great success) it would have comparable ROF to a semi automatic pressure powered blaster.

Edited by Boot, 23 February 2011 - 07:32 AM.

[Split]

I really think you haven't done as much research as you claim.
If you know of most blasters, you've heard of the Big Salvo. Well, besides using the tanks, it is a self contained blaster. It's four shots, staggered fire (pull the trigger a little, fires the first tank, pull more, next tank, etc), and the tanks with a plugged pump can launch three to four 1/2" darts 80-90' easily. It's not really that war practical, but it sounds almost exactly like what you want, with little work (re-barreling and plugging the pump). (Draconis also suggested this solution)

(Thanks to Carbon for the pic)


If you really need it to have a semi-auto trigger and be an airgun, take a hornet and replace all of the tanks with big salvo tanks. It has been done before and works pretty well. If you want to fill it faster, switch out the pump.

^^Ice Nine's beasty


Lastly, the most practical (and coolest) solution is already in the directory. Check THIS out. This thing with 1/2" darts is a monster. (Boot suggested a similar solution in his last edit)



Edit:

Broken SVT recently very kindly introduced me to the triple strike tank. It is a large backpressure tank, larger than that of a Big Salvo, but smaller than a titan tank (it is rare though)

And weaker than you think.

If you really are going for semi auto you should use a back pressure tank. With a pin tank semi auto setups require multiple processes and valves, while in a setup like the Mirage-SS a single simple valve can be used to efficiently trigger a backpressure tank semi automatically.

It's actually only one more process, which is easily linked. The trigger pulls the pin, when the trigger goes forward again, it hits the fill button. Some might even call that easier than the check valve setup and finding particular valves with the right flow rates. Neither setup is difficult.

Regardless, to get a semi auto shotgun spread you will need a Massive fill tank, anything large enough has to be fitted to a backpack, otherwise I doubt any more than about 3 shots per fill is possible (unless you are using some insane HPA or Paintball tank with a regulator.)

There is too much blanket statement here. See the solutions I posted above in regards to how simple the project actually is.

A final possibility could actually be the marshmallow blaster, I'm not too familiar with them, but I think they operate off a backpressure system or something similar.

There is only one line of these that uses an airtank (most are push-pull) afaik and it's a pin-valve.

Also there is this off brand BBBB equivalent called the "blast bazooka" (or words to that effect) which has a tank just shy of the BBBB and operates off a backpressure system.

The LBB (blast bazooka) is virtually identical to a 4B, except that the pin is made of plastic and the tank body is a different color. The Buzzer Bazooka you may be thinking of does have a similar shell to a 4B, and is backpressure, but the tank is tiny. Smaller than a hornet tank I believe. I've owned a few.

Edited by Split, 23 February 2011 - 09:38 AM.

[VelveetaAvenger]

It's actually only one more process, which is easily linked. The trigger pulls the pin, when the trigger goes forward again, it hits the fill button. Some might even call that easier than the check valve setup and finding particular valves with the right flow rates. Neither setup is difficult.

Sorry to hijack the thread, but I was wondering if you could expand on this a bit or maybe link to a write up. I just found one of those air-advancing sm3k's at a thrift store and this sounds exactly like what I need to make it semi-auto. I haven't made anything that uses reserve tanks before, so I don't really know what I'm doing.

[Split]

Sure. Take, for instance, a 2k. The trigger slides along the pump tube just like normal. At the end of the trigger pull, the tank is opened. We've all seen this. Here's an internals pic from the directory (thanks to Uncle Hammer)


So, to make this a semi-auto 2k, you have some sort of external tank/input. This can be HPA, or a hard tank (with or without a regulator), or a bladder, or a compressor or whatever. This tank routes into some open/close valve. The magstrike/powerclip trigger valve, for instance. These are common. Depending on how fast you want your semi-auto, they don't need to be particularly high quality or high flow.

So the air routes into this valve, and the output of this valve goes to the 2k tank. No check valves needed. When the firing trigger goes forward, (the 2k tank pin isn't being pulled anymore) the trigger pushes into the valve. The valve opens, the external tank sends air into the 2k tank. When you start pulling the trigger again, the trigger is no longer opening the valve, and the tank is full of air, ready to be fired. Pull the trigger all the way, it fires. It's a semi-auto 2k.

If you don't want to do the timing and everything of getting the trigger to hit the valve at the right time, you can just put the valve I was talking about somewhere else, and to fire you pull the main trigger, let that go, then hit the valve button, then let that go. Repeat for semi-auto-ish. I can't find the (THIRST?) writeup that had this setup.

Even simpler, just hook the input up to the tank and pull the trigger quickly. Here's a thread with that from almost 7 years ago: http://nerfhaven.com...?showtopic=2840


Semi-auto air guns are icky. They're pretty simple at this point, I think people are just intimidated by the prospect. Hope to see yours working! Let me know if you need help on the calculations for external tanks. I made a nice spreadsheet to calculate the volume/pressure a while back, but it's pretty bland and off-topic, so I won't post it here.

[Dyxlesic]

Split, your work always amazes me. I'm not sure, but I think you misinterpreted the project in a few ways. It will use one exhaust tank, (not 4 or 6 like in the pictures you showed me). The one tank will feed 4 separate short barrels, as I use a variety of only stock darts (not stefans). I am familiar with salvo tanks, as you sold me two. However, I did not get to do much testing with them, as ones seal broke after 3 shots, and the other one exploded, and came inches from putting NMR brother in the hospital, and put a dent in the floor. As I have mentioned, this isn't your fault, and I dont blame you at all. I did not realize 10 magstrike pumps would do that, as I overestimated the volume of a salvo tank.

Since it is only 1 tank, feeding 4 short barrels, do you think a salvo tank would have the air volume and release rate to fire the with usable power?

[Buffdaddy]

+Honestly, you're looking at doing 3-4 shots decent range, so 50'+. You might as well do a Big Blast like BrokenSVT, but shotgunned instead of hoppered. A couple quick pumps off the bike pump is all you need, and that's more than enough air to push everything, with the Tank expansion and all. It's not semiauto, but it's an option, as I'm sure you could swap out "shells" nd pump it up in decent time.

[Inferno Falcon]

I also think a 4b would be the best bang for your buck / effort. A tank expanded 4b can easily fire 4 darts at 50 feet.

[Dyxlesic]

For a 4b, about how many magstrike pumps would I need to use per shot for decent power? I've never used a 4b, so I have no idea on volume or air release speed of one.

[Draconis]

Since it is only 1 tank, feeding 4 short barrels, do you think a salvo tank would have the air volume and release rate to fire the with usable power?

Why limit yourself by using one tank? Using a complete Salvo give not only the shotgun ability, but also individual semi-auto fire.

I also wanted to clarify things regarding the buzzer bazooka and the Sonic Bazooka. The buzzer bazooka is built similarly to the LBB and the 4B, in that the valve is actually a smaller unit with a pin dump valve. But there is also a larger secondary tank with the pump tube glued in to it. This pic doesn't really show much of the tank, but it's there on the left.



The Sonic Bazooka is sorta shaped like a smaller LBB, but uses a large back pressure tank.

[Split]

Split, your work always amazes me. I'm not sure, but I think you misinterpreted the project in a few ways. It will use one exhaust tank, (not 4 or 6 like in the pictures you showed me). The one tank will feed 4 separate short barrels, as I use a variety of only stock darts (not stefans). I am familiar with salvo tanks, as you sold me two. However, I did not get to do much testing with them, as ones seal broke after 3 shots, and the other one exploded, and came inches from putting NMR brother in the hospital, and put a dent in the floor. As I have mentioned, this isn't your fault, and I dont blame you at all. I did not realize 10 magstrike pumps would do that, as I overestimated the volume of a salvo tank.

Since it is only 1 tank, feeding 4 short barrels, do you think a salvo tank would have the air volume and release rate to fire the with usable power?

Well, you have sort of contradictory requirements here. You want low energy input (not a lot of pumping, easy to reprime, tank isn't too big - "NOT titan tank") but also want to use inefficient setups to yield good ranges (high energy output). Stock darts + multiple air flow paths + good ranges. There's really no reason for you to mention how much you overpumped salvo tanks yet again.

There isn't going to be a single tank that you can make semi-auto to feed that setup without having either a huge/high pressure external tank or an entire HPA setup. Just throw a four barrel setup on a high air output springer (or airgun, if you really want). Besides, if you're going for semi-auto, with that setup, you'd have to reload all of the barrels every time = not semi-auto. If you haven't picked a solution by now, this has devolved too far into a concept thread.

Edited by Split, 23 February 2011 - 01:02 PM.

[Dyxlesic]

Split, your work always amazes me. I'm not sure, but I think you misinterpreted the project in a few ways. It will use one exhaust tank, (not 4 or 6 like in the pictures you showed me). The one tank will feed 4 separate short barrels, as I use a variety of only stock darts (not stefans). I am familiar with salvo tanks, as you sold me two. However, I did not get to do much testing with them, as ones seal broke after 3 shots, and the other one exploded, and came inches from putting NMR brother in the hospital, and put a dent in the floor. As I have mentioned, this isn't your fault, and I dont blame you at all. I did not realize 10 magstrike pumps would do that, as I overestimated the volume of a salvo tank.

Since it is only 1 tank, feeding 4 short barrels, do you think a salvo tank would have the air volume and release rate to fire the with usable power?

Well, you have sort of contradictory requirements here. You want low energy input (not a lot of pumping, easy to reprime, tank isn't too big - "NOT titan tank") but also want to use inefficient setups to yield good ranges (high energy output). Stock darts + multiple air flow paths + good ranges. There's really no reason for you to mention how much you overpumped salvo tanks yet again.

There isn't going to be a single tank that you can make semi-auto to feed that setup without having either a huge/high pressure external tank or an entire HPA setup. Just throw a four barrel setup on a high air output springer (or airgun, if you really want). Besides, if you're going for semi-auto, with that setup, you'd have to reload all of the barrels every time = not semi-auto. If you haven't picked a solution by now, this has devolved too far into a concept thread.

While it may seem contradictory, I have a similar setup on a marshmallow blaster of mine. I hotglued 4 crayola barrels on the front of a marshmallow blaster. While it has plenty of deadspace I can't remove between the tank and the barrels, with 4-6 pumps, the 4 stock darts will fly easily 50 feet with stock darts. I brought the salvo tanks up to show that while I may have used them, I did not do much testing, and to show I am not very familiar with airtank volumes and stuff like that.

The air part of it will be semi auto, meaning it shoots a burst of air every trigger pull, but the actoul loading will be manually switched shells between shots. as I said in the first post, I pump action or true semi auto shotgun is way out of my current capabilities, time, and budget. I will upload a hand drawn picture as soon as I can, and a diagram from my computer later on.

Please excuse my digraphic drawings and handwriting. The "?" is the tank I'm trying to decide what to use
And yes, I realize the air tank looks like a penis. Please find it in your perverted hearts to ignore it

Edited by Dyxlesic, 23 February 2011 - 02:10 PM.