20 mm Vulcan barrel

[shelbyclay]

Nice forum here. I have a home made cannon myself made from some 3 inch pipe with a 1.3 inch ID. Havent shot any projectiles yet but it makes a really loud noise with about 3 tablespoons of Pyrodex in it. Ran out of the home made stuff. The neighbors got really upset on the fourth of July. I thought i could get away with it then, guess I will have to find a more deserted place to shoot and test it out with a ball in it. The whole thing is welded together and I will have to put it in a hole to test fire it. I have made a rough carrage until it is tested so I wont have to lug it around in a wheelbarrow. the thing weighs about 75 lbs.
wish me luck.




I noticed a 3 foot, 20 mm vulcan barrel for sale on E-Bay this morning for about 45 bucks. I have been looking for a 30 mm barrel myself. I'm hoping someone here can use it. Sale ends at noon.

[Cannonball]

First off, Welcome to the greatest campfire in cyberspace!

Unless your sure of what type of steel your tube is made from, it's under spec for firing live rounds. The barrel wall should be 1 caliber thick as well as the breech behind the bore.

If your new at this, take a look at some of the literature available at the top of the threads page under "References, books and plans..." or "Where to find black powder cannons...". You'll find a wealth of knowledge there. JJ

[Cat Whisperer]

Shelby -

Let me echo Cannonball's WELCOME, and his words of wisdom - you mentioned the term 'pipe' - that scares a lot of us.

The metal used in cannons is much stronger and is designed to withstand not just  the static pressure (as do some pipe specs) but the dynamics of the explosions.

Pipe = bomb.  For the above reason and pipe can be strong even if it is welded, but if it is welded there will be a porous area along the pipe that WILL eventually fail from the products of combustion seeping into the pores.

[Will Bison]

By all means, Welcome.

That's a sturdy looking tube.

Tell us more about that homemade powder I see.

Bill

[shelbyclay]

     From reading here and other cannon sites, I think I will have to relegate my cannon to a noise maker only.  I have no idea what kind of metal it is. The barrel has a 3/4 inch wall thickness and a 1 3/8 inch bore. It is plugged with 1.5 inch piece of iron rod welded into it and has an additional 3/4 inch plate welded onto the back of that. I also have a 1 foot piece of 4 inch OD pipe with a 3 inch ID that is forced over the rear and is plugged the same way. The trunions are just welded on 1.5 inch stock.

   I had to make my own black powder when I couldnt find anything but Pyrodex locally. EZ directions here.

 http://www.unitednuclear.com/bp.htm.

I bought everything from E-Bay, a few pounds of finely ground potassium nitrate, from a rocket enthusiast, sulfur and air float charcoal from two other sites there. Basic recipe has been the same for a few hundred years, 75% potassiun nitrate, 15% charcoal and 10% sulfur. Put everything in my rock tumbler ( rubber lined), with a box of 50 caliber lead balls from my muzzle loader and tumbled it over night.
I put 3 tablespoons of that mix into the cannon and packed it with a sheet of newspaper real well. It made a shu-shu out of the touch hole for about 10 seconds, what a let down! After that I granulated it, same result. I finally got it to work by putting a starter of 1 tablespoon of FF Pyrodex in first, followed by two tablespoons of the homemade stuff. It makes a spectacular muzzle blast with sparks flying off and also leaves a lot of residue in the barrel. Still it is a lot cheaper than Pyrodex and I love the huge clouds of smoke it puts out, much better than Pyrodex by itself. I am about to make some more. I may try experimenting by mixing a small percentage of Pyrodex in it, if this next batch is still reluctant to go boom by itself.   





I think I need a BB cannon now. At the moment, I am in the middle of the Gulf of Mexico on a drilling rig. I have already talked to the welder about finding an old oxygen cylinder and he has given me a few leads.
With that and a nice swivel gun I should be happy for a little while.


 

[jeeper1]

With that and a nice swivel gun I should be happy for a little while.

Yeah, right up until you fire them. Then you will find you can't own enough.

[Tropico]

Welcome Shelbyclay ., The mix would be better if the  charcoal was at 75% ., I dont know if you have a mis type or if thats really the way you mixed it but if you mixed it at 75% charcoal ...., you might not need the pyrodex., if you get the ratios right.

Basic recipe has been the same for a few hundred years, 75% potassiun nitrate, 15% charcoal and 10% sulfur.

[Cannonball]

I'm just rambling here but maybe for good reason. We all know the powder made today is much stronger than the stuff produced in days gone by, however, homemade and store bought might have very different characteristics. If more sulfur in one produces a more corrosive powder, then maybe more of the wrong ingredient will produce more of a blasting powder than a propellant? If a pre formed charge in aluminum foil was transported over a long distance to the range, and the finer granules settle to the bottom or one side, that side will burn quicker no? Instead of ignition at the rear pushing everything out, ignition up one side first might direct pressure towards the opposite sidewall, no? Like the tests performed by Sam Fadala in the gun digest black powder reloading manual. An over charged gun didn't blow the first time fired overloaded, but a regular charge blew the barrel when it was left loose down the length of the bore and fired. I'm no engineer or rocket scientist but explosives are tricky like that.

I saw a show on the military channel that did a demonstration with RPG warheads. When a block of HE was placed on a 1" thick sheet of steel and set off, it merely polished the surface, make a small indent in the HE and place the indent facing down on the steel and it blew a hole through it. Line the indent with a thin layer of copper and the copper liquefied on ignition  and produced a jet that punched right through 10 inches of steel armor plating! HE and BP are to very different explosives. BP being so outdated in this day and age, mankind has actually performed more testing with modern explosives than we have the one that's been around 10,000 years. IMHO, I'd scrap it! Why risk the destruction (potentially life threatening) of your cannon?

[GGaskill]

The mix would be better if the  charcoal was at 75%.

No, 75% KNO₃ is correct.  75% charcoal probably wouldn't even ignite.

We all know the powder made today is much stronger than the stuff produced in days gone by, ...

Actually the stuff made at the end of the muzzle loading era called "Brown Powder" was more powerful than the stuff made today, almost rivaling the early smokeless.  The major improvement of today's powders is better uniformity.

[Tropico]

75% potassium nitrate, 15% charcoal and 10% sulfur is correct then ?

I have been seriously thinking of making my own and getting the ball mill..., I am going to have to re-read that united nuclear site., many times over and get this right..., I just think it would be fun to do., and also., getting black-powder in the Philippines in a cannon grade may be  tough....., there are fire cracker mills everywhere.., but that's not going to  work for me.

I would much rather learn it in the states then somewhere else..., better advise., better material., and knowledgeable people.., once I get settled there..., I am sort of out in the jungle.

[shelbyclay]

      Thanks guys for all the input here. It's nice to find more people interested in things that go BOOM!
    When my wife sees me cleaning out he cannon on the Fourth or New Years, she hustles to gather the kids into the car and leaves the neighborhood! I was severely worried on the Fourth, a few days ago. Three tablespoons of Pyrodex is MUCH louder than my home made stuff. Everybody here has an acre lot and I have a lot of bushes that screen me from the street. I set it off in the middle of my front yard, As soon as I set it off I heard some kids down the block screaming as they ran inside. The shock wave set my car alarm off from about 40 feet away. I grabbed the back of the carrage and hustled the cannon into the back yard and went inside.  Peeking out the window, I saw the neighbor across the street coming out and looking  up and down the street and peering into my yard. I am sure glad the smoke cloud disapated quickly! He started talking to another neighbor that drove up from the next block and I went out looking properly worried. he asked me If I knew what that big explosion was. I said that I thought it sounded likea shotgun went off. By then two more neighbors had driven up and some one else said "That wasn't no shotgun, it might have been a transformer". Well I started lookiing up at the transformers and said Hmmm, mabey it was a transformer. Of course someone else had to chime in, "I've heard transformers but I have never heard one go off that loud, I live on the next street back and I felt the concussion in my chest!".  I drifted back inside and frantically cleaned the cannon in the garage, oiled it and stuck it under a tarp.
Sat around for an hour waiting for the cops to show up. Never happened but I sweatted it out. I am going to have to go the the range to shoot from now on. Can't take the stress from the neighbors anymore. Got my eye on a nice cannon from Missouri cannons though so I will be shooting balls soon, can't wait.
I think I can get away with mabey one shot it in the yard on New Years if I wait till midnight, wish me luck.