Greetings from Brooklyn, Vic. There are many ways to make cannon carriages and their trucks. Some of the techniques will require tooling, but others, are kinda simplified and don't yield the quality and final appliance. For example, the way you made your tracks from a dowel, is the most common of doing weels. I would say it is a classic method. With practice, you will achieve great results!
Because you are entered a new level of modeling called 'kit bashing', you may add some essential tools at your disposal. If you don't have any rotary tools, get one of those. Dremel or Proxxon will be your choice. We had a great discussion recently about what rotary tool to buy. But carefully plan as depending on your choice, the next tool suggestion is a drill stand. Both Dremel and Proxxon have drill stands for their rotary tools. A combination of a rotary tool and the drill stand will make a very important tool - Drill press. Using this tool, you can drill cannon tracks with precision right in the middle. Obviously, if you have a budget you can simply buy a drill press but...
Dremel drill stand and rotary tool may cost you ~ $100.00 (price based on the 3000 Series 1.2 Amp Variable Speed Corded Rotary Tool)
This is just an example, of how you can improve the way you work. I am NO WAY want this post routed to the discussion of what tool is better: Proxon or Dremel. Everyone has their own preference\budget on brand\tool they will buy. If you have enough budget (is it possible, enough?????
) then you would buy a drill press, to begin with.
As for the present capabilities, you will be surprised by your own capabilities while using the right tools for the given job. Don't underestimate your capabilities! We learn from each other, and it definitely works!