What I'm saying is the largest available mortars to the general public have the easy equivelant charge of a M80, at least the ones in my grimy little paw right this minute here in Wisconsin sure do.
If they do, then are illegal. As mentioned before the feds clamped down on fireworks and you can only buy class C now. I know there is an illegal market for the banned stuff.
Be careful with them. Accidents can happen. Have a safe 4th !!