I asked if it has a breach plug and this is the response.
"It is welded directly to the plate. This construction method has been tested through many cycles over the course of years and is still going strong. If you are looking for different sizes, materials, or designs I can make you a custom cannon."
This design is not safe and I dont think the maker understands the dangers.
I will second that. I wonder how many cases of beer were possibly consumed during the "testing" phase of this product

Piece of pipe of unspecified metalurgical content welded to a flat plate of dissimalar metal with a single pass (mig?) weld that doesn't go all the way around. Gap between the plate and tube, vent drilled nearly to the bottom, doesn't appear to incorporate a 37 degree angle for filler weld, gap between tube and plate obviously goes all the way around as a result of the thermal properties of the welding process incouraging "coking" or hard carbon build up that can result in detonation (while loading) on and on and on........................................You know, its ok if someone wants to live on the edge and endanger their lives, but it aint ok when they feel the obligation to share that danger with others.............Whew, just sayin....................