I've been making 3d printed cannons for a while, and I think this is my most successful design yet. It's another low profile design, this time with the magazine in a large coil shape rather than a tight spiral. It is set up for use as a sidemount, with 20 degrees of down-angle built in.
It also uses a 3d-printed compression nut to hold the barrel, basically the reverse of the traditional arrangement. Rather than having male threads on the cannon and a nut on the barrel, this cannon has the male threads on the barrel and the nut on the cannon. To tweak the cannon, you turn the whole barrel.
The feed ramp for this cannon is very smooth. There isn't much slope though, so it needs a magnet to ensure reliable feeding. I have included a cutout for a 1/4" dia x 1/4" long magnet at the T section for this purpose. One of the test cannons installed in my predreads recently knocked its magnet out from the repeated shock of firing, so ensure your magnet is securely installed.
As with most of my cannon designs, this was designed to be a real gas-guzzler, capable of firing as fast as you can pull the trigger. Using high-flow BC solenoids and short runs of massive 1/8" ID gas line, I have yet to find the upper limit of this cannon's performance. The basic piston profile and internal gas bypass are identical to previous cannons, the only real change is the coil shape of the magazine.
As with all cannon designs provided on this website, this design is provided as-is, with no guarantees about performance. My cannons have worked well for me, but I don't know your printer, your material, or your settings. You assume all risks with printing and using this cannon.