Heres a little video of my first piston gun

[watto]

What do yous reckon



[youtube] [/youtube]

[Killjoy]

That was pretty impressive...and that was a lot of newspaper to be penetrated. Pretty cool.

[watto]

yeh I didnt think It would make it all the way through, Its power definately surprised me.

[mega_swordman]

Ah! you might want to invest in a partner to conrtol the camera. Too much movement. Otherwise it looks good.

[watto]

Yeh pretty hopeless I know, If I was smart I would have also turned on the light....(FARK!)

[jrrdw]

Didn't sound like alot of pressure behind that shot. Any idea how much it was? At that range 18"s or so, i would think the marble would go through all the paper and box into what was behind it. Nice cannon, I like it!

[watto]

Didn't sound like alot of pressure behind that shot. Any idea how much it was? At that range 18"s or so, i would think the marble would go through all the paper and box into what was behind it. Nice cannon, I like it!

The shot was at 90-100PSI I think, the camera must not have a good microphone because the shot was deafening in that small room. The ammo was a round lead fishing sinker not a marble.

[jrrdw]

I didn't notice any wadding. How good of a fit is the sinker? Try some wadding next time, i think it will improve power no dought. I sagest a stronger target or shoot outside to keep from tearing up anything important! How much did the sinker weight?

[watto]

I didn't notice any wadding. How good of a fit is the sinker? Try some wadding next time, i think it will improve power no dought. I sagest a stronger target or shoot outside to keep from tearing up anything important! How much did the sinker weight?

If you freeze the video just when I look at the hole for the first time, you can see the tightly packed clingwrap I used as wadding wedged in the hole, but I pulled it out with my other hand off camera.

The reason I dont shoot outside at my own house anymore is because I always end up putting holes in my fence or getting some neighbour complaining because they had a potato land in they're pool

I imagine the sinker would have weighed around 50g.

[psycix]

Nice cannon.
I am planning to build something similar like that soon.

How long are your barrel and chamber?

[watto]

chamber is 50mmx45cm, barrel is 15mmx100cm. If the boot of my car was bigger I would have made the barrel heaps longer. When you buy 15mm pipe check that it doesnt already have a bow in it, if its bent it can it makes things difficult.

[jackssmirkingrevenge]

If the boot of my car was bigger I would have made the barrel heaps longer.

surely there's some fittling that will allow you to fit a removable extension?

[watto]

Well, I suppose I could get a thread and screw type arrangement, but the threads I've seen around my way tend to reduce the size of the pipe. Even if it didn't reduce the pipe I imagine there would be a quite significant a bump in the barrel from the join. Another possible problem with that is that the rounds I let off, tend to be not on my own property, or anywhere where I should be discharging a firearm, therefor I have to make a speedy exit immediately after the loud shot, so unscrewing a barrel may slow down my retreat.

JSR what do you think the power gain would be from doubling the barrel length (the current ratio is around 5:1) Do you think the 'bump' in the barrel due to the join would create too much resistance?

[jackssmirkingrevenge]

I have to make a speedy exit immediately after the loud shot, so unscrewing a barrel may slow down my retreat.

... but a longer barrel will give you quieter shot

what do you think the power gain would be from doubling the barrel length

The gain would be significant, I don't have GGDT handy but as a guestimate I'd say at least 15-25% increase in velocity.

Do you think the 'bump' in the barrel due to the join would create too much resistance?

It depends what you're firing - for spherical projectiles it wouldn't really make a difference as long as the two sections are in line.

[f.c]

i like the gun. are you an Australian as you seem to measure you're pipe in mm. also what is that song playing in the background it seems very familiar.