9" nails as ammo: New slingshot pumpgun!

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JoergS

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Here is my latest work... a repeating slingshot crossbow, shooting 9 inch nails.

This is in continuance with my Chu-Ko-Nu based design line. This time, it is bigger than the pencil shooter, but a lot smaller than the chest mounted spear launcher.

9inch210.jpg

The ammo is - nine inch (23 cm) nails. Those are cheap, about 8 Euro-cents a pop (10 Euros for 120 of them). Of course you have to cut of the head, done in about one minute.

9inch110.jpg

The repeating action is done by pressing the butt against the chest and pulling back with both arms, like in a rowing machine. This is needed as you need a lot of draw force to throw the heavy nails - each weighs 76 gramms (1276 gr). The magazine fits ten of them.

9inch310.jpg

With a bit of extra effort, you can very easily enhance the tip by sharpening it. I even hardened the tip of this one.

9inch410.jpg

It works great. I may add more rubber soon, but already this is very effective. Like a Chu-Ko-Nu, but more compact and with a trigger!

Here is the video:

http://www.youtube.com/watch?v=95Xm-YT4FZ0
 
Looks like you've reinvented the Chinese repeating crossbow. I'm always delighted at your inventiveness.
 
Wow, rubber band gun of doom...
What do you plan to use this on? Is this some kind of firearm replacement for someone who lives somewhere it isn't possible to get a firearm?
If so... Looks like it would be a good replacement!
 
Here is the video - sorry for the indoor filming, lots of rain.

http://www.youtube.com/watch?v=95Xm-YT4FZ0

The weapon is very good for distances up to 15 ft - then the nails will start to tumble. If you use front heavy bolts (wooden, aluminum or carbon shaft, steel tip), then the effective range is more like 20 yards.

I think this makes a good self defense weapon, much quicker reloading vs. a single shot crossbow and very intimidating. One hit with a nail in the belly, and a burglar/attacker wants a doctor more than anything else in the world :)
 
JoergS, that is about the neatest thing I've seen in a while.

I hope you don't mine if I share your video on facebook.



Also, what are the bands that you are using for this nail gun? I still have a few weeks before school actually starts, and I'd like to attempt something like this to shoot in the backyard.
 
possom813 said:
I hope you don't mine if I share your video on facebook.

Also, what are the bands that you are using for this nail gun?
Click to expand...

Go right ahead an post it on facebook, that's fine with me.

I used Thera Band Gold, 6cm x 13cm, two bands per side (looped). Since the video was shot, I added another identical band in Thera Band Blue, effectively making the bands 30% stronger. This is pretty much the limit of the material (wood is groaning under strain already).
 
It's a good thing it only holds ten "bolts" because we all know that 11 would just be too dangerous.

I love your videos and slingshots. Keep them coming.
 
The weapon is very good for distances up to 15 ft - then the nails will start to tumble.
Click to expand...

Might there be a way to add fins to the back, like an arrow to help stabilize for longer range?
 
The dimensions of the weapon depend very much on the size of the nails. A pattern would really only work if you use the exact same nails I have. It is not likely that this will be the case.

The weapon is very easy to understand, though. Only two moving parts - the trigger/sear and the slide.

As I said in the video, fins aren't the key to a stable flight. Front heaviness is. Fins are important for bows, as they are needed to overcome the archer's paradox (the arrows wobble after the shot). For a weapon like this, there is no such effect as the acceleration is very linear.
 
Very good engineering, an effective weapon built from common materials, using basic skills.
Joerg, my compliments, true strength of intellect and inventiveness.
 
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