First welcome to our board. You will find cannon people of al sorts for all over the world here.
So you want a cannon! First place to look is our stickies and make contact with our sponsors. They can help you out.
You say you want a golf ball size cannon. First understand that is a pretty good size cannon, especially in golf ball bore size. A Napoleon will be about 33 inches long and about 5.25 inches in diameter.
Sponsor Brooks USA is currently building a brass Napoleon in one inch bore for me and the barrel will almost be 20 inches long and 3 inches in diameter in the breech.
Sponsor Ed Hart at HMR cannons is currently building me a golf ball bore size model of the 8 inch siege howitzer. This will be a close 1/5 scale cannon.
Tell us more about what you know about cannons so we can help go in the right direction...
If you are using Steel, what is the wall thickness going to be on a GB cannon? Roughly? Chamber OD? Assuming a safe minimum?
I ask because of the scaling issue. For example that Napoleon 1857 model. Looks to me like a roughly 66" barrel on the full size originals. So at 33"s, thats about half scale. Thats a little larger than what I was thinking. I was thinking more like 1/3 scale which puts the barrel down to about 22"s. Bore from 4.62"s down to 1.7"s. Seems about right from the straight scale perspective. However strength of material would not scale at the same rate. I see a lot of Mountain Howitzers around 24"s for GBs. I understand the barrel profile is larger. So is that just not going to add up?
Anyway, we are thinking around a 24" +/- in barrel length to get us where we want to be. If its just a matter of picking a different barrel profile, thats what we will have to do as we can both live with the Mountain Howitzer look. We just like the 1861 or 1857 cannon look a bit more.
What we know about cannons.... I don't presume to know anything and we are very open minded. I have found that taking advise from those with experience usually works out pretty well! Hopefully I kind of laid out what I was thinking enough for you guys to get the idea of what we are looking to do. Any suggestions from don't do it, to you should reconsider this, to you should do that... will be appreciated! In the end, we will have to make the call, after learning all we can, if its a path we want to travel down or if idea we had in mind is not going to work out well enough to make it worth it to us.