Building a better NERF gun – part 2.

January 19th, 2011

Part 1 of this post is available here: http://www.asciimation.co.nz/bb/2011/01/17/building-a-better-nerf-gun

Click on the pictures to see larger versions.

A film is available on YouTube showing the pistol and how well it compares to a standard Nerf Maverick.

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The main body is simply a length of PVC pipe.  The barrel assembly and the two centering rings are screwed into one end.

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The main spring goes between the piston and the end cap. To assemble this you simply remove the ring from the end of the plunger and push the end cap over the end of the rod then reattach the pull ring.

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With the end cap screwed into place the weapon can be cocked. As you pull back the plunger the telescoping rod pulls out until the internal stop hits the back of the catch. Then as you pull further the rod and piston move backwards compressing the spring. When pulled all the way back the catch protrudes through the end cap. The catch wire is bent so that the plunger pushes it aside as it passes. The catch wire can then move back into the notch in the end of the plunger preventing it from moving forwards again. Once the catch is locked into the notch the telescoping section can be pushed forwards. This is done to avoid having the plunger rod having to extend past the rear of the pistol. To release the piston to allow it to spring forward all you do is push the wire out of the notch.

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The wire is moved by pulling the trigger which rides in a trigger housing. The trigger itself is made from a solid piece of aluminium cut and filed into shape.  This is attached to a flat aluminium plate by two small screws. One screw also holds a small brass tab used to attach the trigger return spring. At the other end of the plate is attached another piece of aluminium with an angled ramp cut on one end.  This piece is the part that actually pushes the catch wire aside to fire the pistol.

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The trigger housing is made from a piece of 22mm wide aluminium extrusion. The housing is what the pistol grip attaches to as well as holding the trigger and trigger plate. Holes in the housing correspond to the holes in the end plate and barrel spacers so that one of the three screws holding each of these in place is also holding the trigger housing to the main body. The front screw also holds the trigger guard in place. At the rear is a small rectangular cut out the catch wire passes through. And there is also a small screw used as an attachment point for the catch spring.

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The trigger and plate slot into the housing and are a nice, sliding fit. The bolt that holds the pistol grip in place passes though the trigger plate. The spacer mentioned earlier is what allows you to tighten the bolt to secure the grip but still allow the trigger plate to move freely back and forth without allowing it to move up and down. With the bolt done up tight the grip is held securely to the trigger housing. The acrylic side plates are then attached with the 3mm bolts. The top of the plates have a step filed into them to fit snugly over the sides of the trigger housing. This prevents both the grip from rotating on the housing and also prevents the side plates rotating on the grip.

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With the trigger guard in place a long screw passes through the housing and guard to attach the housing to the gun body. This screw is also what the trigger return spring hooks onto. The spring pulls the trigger plate forwards. When the trigger plate is forwards the ramp at the rear of the housing is also forward, away from the catch wire.

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When you squeeze the trigger the plate slides backwards. The ramp on the end of the trigger plate also moves back and the ramp pushes the catch wire to the right, out of the notch in the end of the plunger and the pistol fires. The spring then returns the trigger forwards.

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With the trigger housing attached to the body and the catch spring in place you can see above how this works.

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Above you can see how the NERF dart fits into the barrel.

And finally some pictures of the (mostly) finished article.

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Finally a shot showing the advantage of the telescoping plunger. With a straight plunger the pistol would be much longer.

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What’s left to do? Well, it can obviously be cleaned up and painted. I also want to remake the ramp piece on the trigger plate from steel rather than aluminium as this wears too quickly. I could also make a small cover to go over the rear of the gun although this would be purely for looks rather than any functional reason. I would hesitate to paint it black as then you start getting into ‘real looking gun’ terriority and people start getting twitchy and I don’t really want twitchy armed offenders squad members on my doorstep!

The range, well that’s tricky to say since the darts don’t fly that well as they are fairly light. Around 8 – 10 metres or so (26 – 33 feet) the darts are fairly accurate and travel fairly flat. Any more than that and you need to start lifting the barrel to get more range.

In the film on YouTube all shots were fired from 7 metres (23 feet) away. The standard Nerf Maverick can barely make that distance.

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One Response to “Building a better NERF gun – part 2.”

  1. Asciimation » Blog Archives » Building a better NERF gun. Says:

    […] onto part 2 here: http://www.asciimation.co.nz/bb/2011/01/19/building-a-better-nerf-gun-part-2 Posted in NERF gun, Projects | Trackback | del.icio.us | Top Of […]