We eventually went to a Cam-Lock fitting sold at TSC so you can load fast. The end of the barrel has been sharpened to "cut" the potatoe. The PVC barrel is also rifled.
Now that I have a snowblower, I may not need this thing anymore. I will reuse the parts though on some other project I am sure?
I had a piece of heavy 5" inch channel which I used as a die to press the track pieces. I then welded them to a chain. I made the front wheels adjustable to put tension on the tracks. I added an idler wheel linked to a contol on the handle to disengage the drive. While it operates nicely on snow, it is a bear to steer on solid ground with a couple hundred pounds on board.