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A Semi-auto, No-priming Springer

Is it possible? Maybe. Is it worthy? Time will tell.

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#1 Salmon

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Posted 06 February 2008 - 09:47 PM

Ok, so there I was, walking along the aisles of Family Dollar, and I found a very interesting contraption. It was a small toy gun made of clear plastic that shot rubber pellets. I decided to get it just for novelty, and because I was curious. So I got home and tried it out. It got measly range, 15' at most, but then I realized that its barrel was pathetic, as was its plunger. But then I took another gaze through the transparent plastic and realized that it had no spring! Or so it seemed. Turns out, it was controlled by a torsion/return spring that was pressed against the trigger(perhaps weakly glued) that lightly pushed against the trigger, and then the end of the spring was glued to the end of the tiny plunger. So what happened was, you put the magazine in, pulll the trigger and release it quickly, and the plunger rod flies forward and hits the pellet out of the barrel. I thought about this for a while, got on MSPaint, and drew my self a diagram of how to (possibly) convert it to a homemade foam-spitter. My only problem is, it would be SUPER hard to pull the trigger, because my homemade gun idea has a compression spring as well as a torsion/return spring thingy. And it would probably not get good range. So, without further adieu, here it is, my MSPaint. And my question to you is, is it possible?

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Edited by Salmon, 06 February 2008 - 10:22 PM.

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#2 CaptainSlug

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Posted 06 February 2008 - 10:37 PM

What you're describing is just like a push-pull mechanism like what is used in the Arrowstorm. Good luck trying to prime an Arrowstorm with one finger.

You're misunderstanding how it works though. The secondary spring is just used as a return for the "trigger". The action is having the plunger pulled back and released one it gets to the end of the priming cycle.


Semi-automatic springer is kind of an oxymoron anyways. The amount of force any of your fingers can comfortably pull on their own is only around 4 or 5 pounds (2 or 3 being much less strenuous). And that's not enough to propel a foam dart any useful distance.
To reach 80 feet you're going to need a minimum of 15 pounds of force pushing a plunger that has a diameter of atleast 3/4".

Edited by CaptainSlug, 06 February 2008 - 10:42 PM.

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#3 Salmon

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Posted 06 February 2008 - 11:15 PM

Semi-automatic springer is kind of an oxymoron anyways. The amount of force any of your fingers can comfortably pull on their own is only around 4 or 5 pounds (2 or 3 being much less strenuous). And that's not enough to propel a foam dart any useful distance.
To reach 80 feet you're going to need a minimum of 15 pounds of force pushing a plunger that has a diameter of atleast 3/4".

Ok, I got it. But one thing I don't quite understand is the part I quoted above. Doesn't a spring just need to compressed? Or does it depend on how hard you pull it? Or is it the first, but you have to exert some amount of force anyways on the trigger? And is there any way if I did make this I could make the trigger pull easier?

Anyways, thanks for replying. Its my first thread, so I was kind of nervous. :blush: I hope more people will reply!
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#4 Carbon

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Posted 06 February 2008 - 11:22 PM

A spring just needs to be compressed, but to get any kind of useful distance, you'll need a strong spring. And the design you have is pulling back the spring with only your trigger finger. That's why all nerf guns have a separate handle for charging the spring...it's too hard to do it with one finger.

Flaming Hilt was discussing ways to do this in his homemades thread. If you were to make it easier, it would require some manner of lever/gear/pulley/something to reduce the work needed to charge the spring. The leverage problem is a hard nut to crack, if it's possible at all.
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#5 CaptainSlug

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Posted 06 February 2008 - 11:25 PM

You are using a spring to store and then release kinetic energy. The spring can release the force much faster and more precisely than you can to push the plunger to fire the dart.
The amount of force stored directly translates to the amount released. The efficiency of this release to the target medium is dependent on many factors though.

In both pump and spring powered blasters you are using your muscles to the fire the dart indirectly. What is different is how the energy is stored and then released.


To reduce the force needed to actuate a trigger you have to use a weaker return trigger, and make the release mechanism as sensitive as possible. Either by limiting friction, or use of leverage or gearing to multiple the input force of the trigger pull a bit. However leverage and gear systems can only multiply so far before you reach the limitations of the materials they are made out of.

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Edited by CaptainSlug, 06 February 2008 - 11:27 PM.

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#6 imaseoulman

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Posted 06 February 2008 - 11:48 PM

I do have an old, off-brand gun that works like a push pull gun (like an Arrow Storm not a fast blast) powered only by the trigger. The trigger is, however, a full hand squeeze. Ranges are, as expected, quite pitiful (comparable to that of an Air Tech 1000...you know that little four round turret gun). It has an eight barrel turret with great ROF. I guess it could be slightly useful as a side-arm in an indoor war.
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#7 precisionnerfer

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Posted 07 February 2008 - 10:56 AM

Salmon, you asked in the titile of this thread if what you speak of is possible. I can tell you now that it is, but it will be horrible if you or anyone makes such a gun. Priming Springers own. It's a great thought, that such a thing might be useful but it will be a huge pain to fire or the range will be about 20" angled.
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#8 Salmon

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Posted 07 February 2008 - 02:32 PM

Oh, all right. :( Kinda dissapointed, cuz I thought "Ya know, that would be one heck of a gun if you didn't have to prime it" but, oh well. Maybe someone much brainier than me can make something like this better. I'll be waiting, CS, Carbon, FA-24, etc. B)
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#9 nerfer192

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Posted 07 February 2008 - 08:57 PM

Ok, so there I was, walking along the aisles of Family Dollar, and I found a very interesting contraption. It was a small toy gun made of clear plastic that shot rubber pellets. I decided to get it just for novelty, and because I was curious. So I got home and tried it out. It got measly range, 15' at most, but then I realized that its barrel was pathetic, as was its plunger. But then I took another gaze through the transparent plastic and realized that it had no spring! Or so it seemed. Turns out, it was controlled by a torsion/return spring that was pressed against the trigger(perhaps weakly glued) that lightly pushed against the trigger, and then the end of the spring was glued to the end of the tiny plunger. So what happened was, you put the magazine in, pulll the trigger and release it quickly, and the plunger rod flies forward and hits the pellet out of the barrel. I thought about this for a while, got on MSPaint, and drew my self a diagram of how to (possibly) convert it to a homemade foam-spitter. My only problem is, it would be SUPER hard to pull the trigger, because my homemade gun idea has a compression spring as well as a torsion/return spring thingy. And it would probably not get good range. So, without further adieu, here it is, my MSPaint. And my question to you is, is it possible?

Posted Image


Ah yes, my frind had one of those and i borrowed it for a while, and i have had an airsoft type gun like this where you pull the trigger all the way back ad then SNAP it fires. Am i right? And yes, it would be very hard to pull the trigger with a huge spring to get enough range. For that you could try using a set of gears to reduce the pull needed to store the potential energy.
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#10 Captain

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Posted 13 February 2008 - 09:22 PM

Maybe you could transfer that pulling motion from the trigger to a shotgun-like foregrip, so much more force can be applied. That should work.
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#11 sputnik

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Posted 13 February 2008 - 11:41 PM

Is this the gun?

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