Both sizes will work as long as you can pour steady.. be sure and take a brush and scrub the inside of that PVC before you seal the one end (if your going to seal one end). I made mine three and a half inches long. Then when I made a couple, I secured the cap on the one end. On the other end I then used some tape to hold the cap in place and also alert me as to what end is loose.

Not too long ago, I was fortunte enough to purchase 100 tubes and caps from a forum member. These clear plastic tubes work perfect. Because I can see the powder charge and know what I have inside. There are companies on line where you can purchase these small tubes and cap and make your own for a lot less money then the speed loaders.