Weird Pressure Question

M

Model12Win

Moderator
Hello all! Now this is a weird one, even for me to ask!

I am trying to commission someone to build me a replica of a 14th century bronze handgonne (hand cannon). If you click "Medieval European Handgonne #1" HERE you will see the .55 caliber original bronze specimen I am trying to have recreated for me. I am going to have it made in .540" caliber so I can use .54 cal balls and patches that I already have plenty of. This specimen seems to have a thick barrel, as most handgonnes do, and tapers to the end. The breech should be something like an inch and a half wide, and the muzzle looks to be about an inch wide with .55 bore.

So, assume we are using a traditional bronze of 88% copper and 12% tin, and I was using 230 grain .535" lead round balls with a thin patch, and maybe up to 40 grains of FFG black powder, and a simple bronze barrel of the dimensions shown in these pictures, how safe do you think that would be? What kind of pressures would said load produce?

I have seen people make reproduction handgonnes in brass and fire them, so I am curious. Of course I could always just have one made from steel, but I would love to have an authentic one made of bronze.

So what do you guys think? Will this be safe provided I don't overload it? Thanks!
 
Pretty sure it'd be okay.

With 40 grains of FFG you'd be most likely looking at pressures somewhere below 8000 psi, if confined, which it won't be since it's thicker on the inside then on the outside and loaded from the front the gas can just escape to the sides of the ball.
 
I think pressure wise you would be safe if it was properly made . Bronze however work hardens .eventually turning into a grenade at the end of a pole .
Probably one of the reasons your having an issue finding someone to make you one .
If you did I would be willing to bet it would be un drilled for the touch hole .
A safer option would be to go with a yellow steel alloy .
Might see Ed Rayl about his muzzle loading barrels
Past that , if you must have bronze . I would line the bronze barrel
 
Bronze was once known as "gunmetal" because it could be cast better than iron. In the muzzleloading cannon era, iron guns were considered cheap and nasty when not outright dangerous.

Wiki says standardized admiralty gunmetal is 88% copper, 10% tin, 2% zinc.
Doubt the handgonne makers were so careful. But they didn't have liability lawyers, either.
 
I think there may have been a reason that a 'handgonne' was not in the hand, but on a (longer is better) stick. And one could take something from the spelling and meaning thereof.

That said, considering your location, you might want to consult with
www.kansascannonworks.com if you don't already know of them. They may have some suggestions or such. Weight at that length may affect your choice of materials too.

There is a thread on ar15.com about mini cannons with links that may be relevant..or not. It seems to me that basically a mini cannon 'on a stick' (nod to Jeff Dunham) is what they were.
https://www.ar15.com/archive/topic.html?b=1&f=5&t=1511655

I have seen minis at shows...they look like fun, but are expensive.

Be Careful!!!
 
Fort Bend iron works in Fort Bend Indiana is who builds most repros. I havnt delt with them in several years but they will be your best bet.
 
I have a neighbour who works in whatever metal which can be machined, but other side of the world.

There's got to be small time machine shops which can do it for you if you provide the blueprints, though.
 
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