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Messing With Oprv On Pumps

Alternative to plugging

4 replies to this topic

#1 louiec3



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Posted 28 January 2010 - 08:09 PM

Well Homa inspired me to do this; it took about 15min and little thinking.
This mod will let you increase the strength of stock nerf pumps so you can get high pressures while still retaining the OPRV.
I did it with a 3k pump but I am sure it will work on pretty much everything.

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Start by cutting off the pump head about 3/8 away from the end. Use a pipe cutter not a saw.

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These are the pieces that should come out.

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Dremel out the pump head, and dremel down the pump shaft. When you're done they should fit together tightly.

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Add a small spring inside of the stock spring. Don't go overboard otherwise it might not work.

Assemble everything and use super glue or epoxy to put them back together. Make sure you apply pressure to the pump while it's drying.
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Here is a nice little video for you.
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There is more dead space in the set up because I only had a tubing tee available so I used a magstrike pump as an endcap of s
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#2 Keith



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Posted 28 January 2010 - 08:23 PM

That would be really handy to be able to get higher pressure, but still have an OPRV. It seems like JSB posted something once about some pumps having a screw that could be tightened to achieve the same result. I think the one in his example was a 4B.
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#3 meatballica



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Posted 29 January 2010 - 10:51 AM

I like this idea. I thought about doing something similar but I could never get it to wrok right because I lack proper tools. Either way I may have to try this sometime.
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"You've waged your war on nerves, but you can't crush the kingdom."

#4 Daniel Beaver

Daniel Beaver


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Posted 29 January 2010 - 02:20 PM

I assume it would be possible to achieve the same result by wedging something under the spring?

I like this idea. I always am tempted to over-pump my blasters.
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#5 cheesypiza001



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Posted 30 January 2010 - 06:52 PM

Just in case it helps you, I'm gonna paste in a part of a thread that I made just like this a while ago.

Also, the AT2K should be a really cool choice to start playing with OPRVs - first drive out the metal pin holding the pump head onto the shaft, then carefully drill out the bottom of the OPRV - by hand so you don't ruin the spring - and then you can make a different length pin to shim up the spring, or insert another spring, a different spring ... anything you like. You can insert parts, and pin it back to the pump shaft - test as many combinations as you like - without the need to glue anything in place.

(note: I've studied it and am confident that should work, but have not in fact actually done all that to an AT2K pump just yet)

I just followed your instructions. However, I cut the plunger head in half in order to open it up as opposed to drilling from the bottom. Here is a picture:

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The springs at the bottom are an assortment of spring that are similar to the stock OPRV spring. I'm pretty sure the stock spring is on the top and the one I replaced it with is right below the stock one, though I may be wrong.

I then took out another piece of plastic that was in between the upper and lower half of the plunger head.

Lastly, I gooped the sides up and clamped it together. Some more pics:

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