Introduction
My modified Nerf Longshot (nicknamed: Leviathan) is a significant powerhouse compared to most stock foam dart blasters. Although I have yet to measure the muzzle velocity of the Leviathan, I can visually notice double the muzzle velocity compared to stock nerf blasters, at least 140 feet per second (FPS) versus 70 FPS. The reason for a high FPS comes down to a powerful spring pushing a plunger forward in an airtight tube to force air into the firing chamber where the dart lies, propelling the dart through an airtight inner barrel for a high muzzle velocity. However, the plunger needs an O-ring as an air seal, and worn-out O-rings will slip off the plunger, disabling the blaster. I will show you how to replace the O-ring in this guide.
Tools
Parts
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You can tell the blaster is not primed when the spring pushes the front pump handle or side handle.
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If the blaster is primed, you can release the spring tension by pulling the trigger.
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Remove the outer barrel attachment and optic.
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If your optic is attached via a Picatinny rail, also remove the rail by reversing the installation steps.
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Remove the screws from the pump-action handle using a Phillips #00 screwdriver.
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Remove the six screws from the stock using a Phillips #00 screwdriver.
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Remove all screws holding the blaster shell together using a Phillips #00 screwdriver.
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Two screws are longer than the rest.
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Two screws are shorter than the rest.
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Lift the top half and set it aside to reveal the internals.
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Remove the screws from the arch holding the plunger arm and plunger tube in place.
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Remove the plunger tube.
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The orange nerf rail tooth and corresponding spring may fly out during the fix. If so, neatly set them aside, but make sure to reinstall during reassembly.
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Remove the screws connecting the plunger tube end cap to the plunger tube using a Phillips #00 screwdriver.
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Pull out the plunger to reveal the worn-out O-ring on the plunger head.
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With all maintenance completed, the Leviathan is back on the hunt. Good hunting, Nerf snipers.