I have a 1/2 inch or 12 MM that I have been using with great sucess with quality sheep casing. Now I do use a 5lb. LEM stuffer, and I only buy quality casings, I happen to get mine cuirrently from Butchers and Packers, they also furnish my cure. Just remember if you are not a yankee to not laugh while on the phone with them....LOL
Mummel, I most HIGHLY suggest a dedicated stuffer, and not trying to use a grinder. Too much heat involved. I have the LEM 5# with SS tubes and love it, its perfect for me. I was using a manuel and with it I would have quit attempting sausage had I not. Course I also got the finest grinder, when I can find something to grind I have a smile from ear to ear all day. It is sooo fine.
You'll learn as you start making sausage, and believe me I am no expert only a novice learning, heat is your biggest enemy! It makes grinders work harder, it makes mixing spices harder, it makes loading the casing harder, and believe it or not, its really tuff to make that magic cooking number.
Anyway, back to your original question, I've got a 1/2, 3/4, and a 1" tube with my stuffer, been able to do everything I wanted to do so far, including snack stix.