I noticed this glitchy keg and played around with how it may have been made. Is this a known issue? First I grab an empty keg, put a few potions in it, and stuff it in a box in my house. Then with no empty bottles in my backpack I use the keg and select the empty bottles that are already in the box. Once the keg is fully depleted it is now 19 stones. Not a very interesting bug/glitch and it really doesn't seem like it has any potential for being exploited. Thought i'd share what I found though.