JonathanRyan.org

Hal and I have been building a Nerf sniper rifle for a while now. It is actually pretty simple, but I’ve been lazy about buying the last few parts. I’m posting from work right now, so I don’t have pictures. Instead, you’ll get whatever I can find online that looks useful.  I have included a diagram of the gun drawn in paint at the end.

The Concept:

The gun needs to be easy to wield and support multiple shots easily. We decided to use compressed air instead of a bolt-action to propel the dart. To support multiple shots, firing is a two-stage process. First, air is bled from the storage tank into the firing tank. Once the firing tank is charged, the trigger is opened allowing the air to push the dart down the barrel.

The Tank:The tank is made from an empty two-liter pop bottle. I put a tire valve in the cap to make it easy to fill. I bought the valve from Belle Tire. It is designed to bolt into a hole, so all I had to do was drill a hole in the cap of the bottle and tighten the valve in place. I found this picture at Ask Mr. Science. It looks pretty much like what I did. The tire valve makes it easy to charge with a pump or air compressor. It also allows me to carry spare pre-charged tanks that can easily be screwed into the gun.

Charging the Firing Tank: Getting air into the bottle is easy, but getting it out of the bottle and into the firing tank is more difficult. The valve doesn’t let air out unless the pin in the middle is being pushed down. After some googling, I found something called an “in-line screw down tire deflater”, and bought a set of them on eBay. They screw onto a valve stem and push down the pin. They also have treads on the other side that allow you to screw something else into the back. I got the image from this site, which also sells them. The deflater was the right size to screw into the small end of a blowgun that I got from an air compressor fitting starter set at Menard’s.I don’t have an actual firing tank, but instead simply use the hose that connects the blowgun valve to the trigger valve. At the moment I am using a huge coiled hose that came with the starter set, but I will switch to a smaller, nicer looking hose eventually.

Firing the gun:

The firing valve is a garden hose nozzle. Squeezing the handle lets the air out of the charged hose and into the barrel. The barrel is about four feet long, so there is plenty of time for the dart to accelerate. Right now, the gun is reloaded by removing the barrel and putting a dart in the end. Eventually I plan on building a breach for quicker loading. I have not been able to test the gun yet because I still need to buy some goop for sealing all of the threads on the fittings. There are small leaks on each end of the hose that needs to be charged in order to fire.

The Final Layout:

This picture doesn’t show any of the structure to hold everything together, but it contains all of the parts necessary to make it fire. You can also see how the PVC of the barrel is attached in a way that gives the gun a stock so the gun is easy to wield.

Once the gun is complete, I’ll upload pictures and report on how well it fires.