Xtreme-patator

[nitrogigi]

Hi guys,
i'm presenting to you my new project :
a hybride canon that will shoot 16mm glass BBs (kids toys ones), at 10 bars pre-pressure (~150PSI) for the first tests, and eventually, up to 300PSI
Chamber will be made in steel, with a welded plug, canon will be a copper tube, 3 points flash ignitor, integrated gas tank, 2 buttons to push to reload (plus reloading ammo).
I'm aiming at 20~30 Joules, to shoot invading nutrias on my pond

Conception isn't finished yet, but it will look like this :

[hectmarr]

The gun looks nice, in general. How do you plan to measure the air-fuel mixture? On the other hand, keep in mind that the copper barrel is not very solid at 300 psi, and it is under high pressure ... if you can get a tube of steel, that is better. I have tried it with a 7X hybrid copper tube, in .25 caliber, and after a few shots, it is wrinkled like an accordion inside, useless. In the first section, the first third of the canyon, it is enlarged, useless.

[mrfoo]

Nice.

Comme dit hector, le cuivre ne risque pas d'aimer cette utilisation. Tube acier sans soudure Ø20, ep2 te donnera Øint de 16mm, ce n'est pas trop cher - https://lamtechno.com/tube-acier-de-pre ... -095_metre par exemple pour ~11€ le metre, (mais l'acier prends un monstre coup a ce moment), c'est un produit assez courant donc trouvable un peu partout.

translation of my rotten french

As Hector says, copper isn't going to like that. Non welded 20mm steel tube with a wall thickness of 2mm will give an ID of 16mm, it's not too expensive - around 11€ a metre, but steel prices are going through the roof at the moment. It's a common product that can be found all over the place.

[nitrogigi]

OK thanks !
I planned to put 3 layers of copper, but I'll go for steel.
I'm currently designing a meter that will be adjustable in volume, for the different mix.
Air pressure will come from a paintball airtank or a pump that goes up to 3500 psi to fill paintball tanks

[Moonbogg]

150-300psi pre pressure is what, 10-20x roughly? Definitely use steel for everything. Other than that, it looks pretty nice!

[hectmarr]

150-300psi pre pressure is what, 10-20x roughly? Definitely use steel for everything. Other than that, it looks pretty nice!

Yes, between 10 and 20x

[jackssmirkingrevenge]

Bienvenu!

I'm aiming at 20~30 Joules, to shoot invading nutrias on my pond

One little note, we do not discuss shooting anything but inanimate objects on this forum.

I made a little HGDT model of your idea wtih a modest chamber of about 100cc volume and a 75cm barrel and... 20-30 Joules? Even at 10x you're an order of magnitude above that:



With a 1000 psi burst disk, your glass marble is well above the speed of sound and you're almost at 500 joules of muzzle energy...

I tried some more modest parameters - 50cm barrel, 50cc chamber, 5x mix and 300 psi burst disk:



You're still over 3 times more than the upper limit of your energy goal at 140 Joules...

[nitrogigi]

My chamber will be 27,3mm in diameter and 200mm long, Canon will probably be 1m long.
For the moment I will be at mix 5.

Could you please simulate aswell with a 6mm diameter barell, 0,84g steel ball, 1m long, 50cm long and 66cm long please?

[jackssmirkingrevenge]

Voila with a 1 meter barrel:



50cm barrel gives 319 m/s and 43J, 66cm gives 356 m/s and 53J

[hectmarr]

Voila with a 1 meter barrel:



50cm barrel gives 319 m/s and 43J, 66cm gives 356 m/s and 53J

wow is supersonic!!

[jackssmirkingrevenge]

wow is supersonic!!

I imagine some of your creations also exceed the speed of sound even though your projects focus mostly on function and not maximum performance.

[hectmarr]

wow is supersonic!!

I imagine some of your creations also exceed the speed of sound even though your projects focus mostly on function and not maximum performance.

It is possible although I don't really know.
I have shot 6mm bb of 0.23gr plastic, with my hybrid gun at 7X, and I think it is more than the speed of sound. I can boom a hard can from both sides and the bb won't break. Note, although the distance to the target is no more than 6 meters, the sound is different from when I shoot lead pellets.
I am working at no more than 8X, generally 7X, due to the limitation of the materials and construction techniques that I use. I can only improve the "function" of the prototypes, as you well say, because it is dangerous to try more pressure and more power with materials that cannot withstand more pressure and power ... This hobby strategy allows me to maintain interest and power. make improvements to my upgraded stuff, within obvious limitations. I still have a lot of fun with these things!