What is the best potato cannon?

Ok, I have seen a lot of variants on potato cannons (here on instructables as well as all over the internet) and have a few questions:
1. What is the best best cannon design?
2. What is the best propellant?
3. What is the best ammo?
4. What is the best barrel size?

Valkyrie103 (author) 7 years ago
I want something that packs a HUGE punch, and still be semi portable ( I do have a system/place to mount it). Preferably something that also has very good range.
lemonie7 years ago
What do you want it to do? Best for what?
Sink a ship?
Be portable?
Tip - the best ammo is a potato - are you asking about a variety?

 A portable one would be fun!  Pocket sized!