I've got several different types of tubes. The majority are an opaque virgin PVC that .38 bullets came in years ago that are still good. You can see the bullets through the walls in good light, but they aren't clear. I've got about 100 of those tubes for .38/9mm bullets.
For .44 and .45 bullets, I've got both polycarbonate and PVC tubing. The polycarbonate tubes are clear, and the PVC are solid. You can also use PETG tubing, which is quite a bit cheaper than polycarbonate.
This link should take you to the PETG tubing:
https://www.mcmaster.com/#standard-p...ubing/=17ei43m
The sleeve for the bullet feeder is a "loose" 5/8" inside diameter, so 5/8" OD tubing will fit correctly. You can use 1/2" OD tubing, but either make a sleeve out of thin aluminum tubing for the inside of the sleeve, or wrap the tubing with electrical tape to make it 5/8" diameter where it fits in the sleeve.
For the .44/45 bullets, I use tubing that is 5/8" OD and 1/2" ID, which is a 1/16" wall. For .38/9mm bullets, you can use 5/8" OD and 3/8" ID, and not have to do the sleeve or tape.
Hope this helps.
Fred