A friend of mine named Foster recently gave me this great little mini cannon he made from our material as a gift. It uses actual black powder and fires a small lead BB.

He also provided step by step instructions for other people to replicate, which are included in this post.

We decided a test firing was in order! So we headed down to an empty park, set up the target, and put a couple mini cannon balls into it.

Simple construction – Materials and Steps

mini cannon


The mini cannon consists of five pieces.

  1. A length of 1″ dia 304 stainless steel round bar – for the cannon. Get a piece about 2.5 – 3″ long.
  2. A piece of 1″ x 1″ x .25″ hot roll angle – for the carriage. Get a piece the same length or slightly shorter than the steel bar.
  3.  One threaded steel bolt
  4. Two washers (optional)
  5. One steel nut, wingnut, or small plastic knob

Alternative Materials

Foster built another one of these a few days later using brass for the barrel and carriage.

  1. A length of 1″ dia 464 Brass Round Bar. Actually, 464 Brass is used to make full sized black powder cannons, both historically and with modern reproductions.
  2. A length of 1″ x 1″ x .125″ Brass Angle.


Use a drill press for this if you have one. You will be more accurate and the barrel will be straighter. Also, Foster got the bar a little oversized and machined it down to exactly 2.5″ long. This is unnecessary but he’s a perfectionist.


  1. Drill the main barrel, a shaft 1.5″ long smack in the middle of the bar. Make sure the barrel is slightly larger than the BBs you want to use.
  2. Drill the vent, a small hole at the end of the barrel, 1.5″ back. This is the trickiest part because you need to drill just enough that the vent connects with the barrel but you don’t accidentally drill a divot into the other side of the barrel. Also, the vent must be smaller than the barrel. Excess gasses will escape from there, and the larger the vent, the less efficient the mini cannon will be.
  3. Make the pivot hole. The pivot attaches the mini cannon to the carriage. It also allows you to aim up or down. To make the pivot, drill another hole completely through the cannon about .5″ from the back. Line it up to be perpendicular to the vent. This makes sure that the vent will be facing up once the cannon is mounted. Drill a matching hole in one leg of the angle, about .75″ from the edge and top. The hole must be the same size as the bolt. You want to allow the cannon to pivot but not be loose or rattle.


  1. Place the bolt through the pivot hole in the angle.
  2. Slot on a washer.
  3. Slot the cannon onto the bolt, make sure the vent is facing up.
  4. Place another washer and put on the nut.

Boom! Now your cannon is ready to fire. Loosen the pivot nut to aim up or down then tighten it again when you’re happy.

mini cannon

A side view cut-away of the angle (left) and cannon (right) for illustrative purposes. Not to scale.

mini cannon

Foster rounded and tapered the edges on the angle, but that’s entirely for style. The muzzle is slightly tapered as well, which makes loading easier. And the little wooden powder scoop doubles as the ram rod for the ball.

Some extra flair and quality of life ideas

After the initial model made from Steel, Foster continues to refine the design. Here are some pictures of his version 2 and version 3 models. Version 2 was built using Brass Hex Bar. This was purely for aesthetic flair. You’ll also notice markings on the side. Because that piece of Hex used to be a measurement piston in a ship engine! Also, he replaced the nut with a wingnut, which makes adjusting the cannon even easier.

For the version 3 DIY mini cannon, Foster used Brass Round Bar. He used a drill press to make the tapered “bowl” at the barrel of the cannon even more pronounced. This helps make loading powder even easier. Similarly, he also made a slightly tapered bowl for the fuse vent on the top. This makes it easier to load powder for the fuse and reduces spillage. Also, the wingnut of version 2 was replaced with a small plastic knob. It wound up being comparably easy as the wingnut.

You may also notice that there is a thin strip milled flat on the Brass rod. That is purely for aesthetic design.

Loading and firing the Mini Cannon

Here’s a bit of trivia for you. During the 18th and 19th centuries, the five-man cannon crews in the British army were assigned a number between 1 and 5. Their number told them what they were supposed to do during the loading process and in what order. This is where the phrase “do this by the numbers” originates from!

The first step of loading this mini cannon is to put a small amount of gunpowder down the barrel. We are talking about a little more than half the size of the nail on your pinkie finger sized.

Next, put the ball into the barrel and use a ramrod to shove it all the way to the back. Use something made from wood, padded, or that won’t ever risk making sparks when it slides along the barrel.

Then, prime the vent for firing. Originally, my mini cannon was supposed to have a fuse. But the ones Foster ordered wound up being too large to fit into the vent. So instead I just piled a little extra black powder on top of the vent to fill it and lit that.

Now you’re ready to aim and fire! Ignite the fuse/powder at the vent to fire. If the vent fizzes but doesn’t go off, wait a minute and try again. Do NOT LOOK DOWN THE BARREL if it fails to fire.

Safety notes

It goes without saying that any time you are dealing with black powder or projectiles, some risk is involved. Therefore, don’t aim at people, animals, or anything you don’t want to risk breaking.

Again, NEVER LOOK DOWN THE BARREL. This is especially true if the cannon is loaded. You’ll shoot your eye out, kid!

After you’ve fired, wait a minute or so before loading it again. There is a slight chance that there may be some powder embers still in the back. If that is the case and you try to load more powder, it will go off prematurely. On a cannon this size that’s less of a concern than with full sized ones. But still, safety first!

Lastly, black powder devices are mechanically inefficient. When you fire, you’ll notice that smoke and unburnt powder shoots out of the barrel and also out of the vent. As such, don’t lean over the vent when firing. You’ll catch grit and that unburnt powder in your face. Trust me, I’ve done it before and it’s no fun. On that note, eye protection is always a good idea.

mini cannon

You can clearly see what I’m talking about on this larger cannon.

With all of this in mind, be safe and have fun! If you make a mini cannon of your own, or even just part of one, please send us pictures. We want to see!

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