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taiden

Member Since 12 Dec 2009
Offline Last Active Jan 30 2011 08:57 PM

Topics I've Started

My Spring Chamber Modification

06 January 2011 - 03:53 PM

Hey all, I apologize if this has already been talked about on here. Still, it may add some fuel to the fire in all of your minds for some modifications you are thinking about making to your NERF guns. I just want to point out that I have been waiting a few months to post this, due to the wait for new accounts. I just want to tell the moderators that I'm sure you have your reasons for this wait, but if I hadn't come across my notes today I wouldn't have bothered to post this because of that waiting period.

Here goes

This is my first post on Nerf Haven and I hope that someone will find it useful.

I stopped modding nerf guns in 2005, I just lost interest. I had a 4 barrel AT2k and a singled AT2k, that was all I needed. I am in college now, and a few of my friends decided to go buy nerf guns just for the heck of it. This sparked my interest in modded nerfs again, and I came on this forum to do some research. Of the current line of guns the Nite Finder seemed like a good starting point. I had never worked with a springer before, it was cheap, and it seemed easy enough to mod.

After performing a CPVC barrel mod, AR removal, double o ring mod and 7/8 x 4 x 0.080 cut spring swap, I was seeing good improvements. I especially loved how you can vacuum load a dart with a springer, while my old AT2k required a ramrod (I didn't have a pvc coupler on it).

I was finding however that if I vacuum loaded a dart and then shot it very soon after the range suffered significantly. I thought about this issue and found a solution.

Let's begin. I apologize in advance if I am too verbose.

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This is the basic dart, barrel, cylinder and plunger model. Note the double o ring mod. Without it, this writeup is completely irrelevant.

On the left is our stefan, which is loaded inside our barrel, which is eventually stopped from being sucked into the cylinder by some wire. Then we have the sealed plunger and cocking shaft inside the cylinder.

This is the way it was set up BEFORE I addressed the issue.


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When you vacuum load the dart, the dart will reach it's furthest point before the cocker is in the fully back position.


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This causes a significant vacuum inside the cylinder/chamber due to the fact that your stefan is well fit to your barrel and sealed, and your double o ring mod and lubrication choice is also sealed.

If you sit and wait half a minute (approx) all the air will be sucked around the dart and the pressure inside the chamber will reach equilibrium with atmospheric pressure. If you fire it before this half minute is over, your range will suffer.



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THE FIX:

I found the plungers position in the fully cocked state and drilled a very small hole right before it. It will be known in this writeup as the 'pressure release hole.'


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Here is a picture showing the pressure release hole.


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Your dart vacuum loads just like before because the system is completely sealed.


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Vacuum occurs for 90% of the plungers range of motion.


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Then as soon as your plunger is in the fully cocked back state, the hole is introduced to the system and the pressure inside is quickly back to atmospheric pressure. The vacuum is lost in a split second!


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When the gun is fired, the plunger passes over the pressure release hole before any significant pressure is built up. The system is quickly sealed and the dart fires just as if it has been loaded down the end with a ramrod.


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Finally, the dart is fired out the barrel, which is all we are aiming to do anyway. It is fired with consistency.

The time from vacuum to equilibrium within the chamber is reduced from 15-30 seconds to less than a second. I have found that this is extremely useful with tight fitting darts. I have increased my range with nerf micros by 10+ feet after this mod. The quicker you shoot after loading the more this will help you.