lol...couldn't work but great photo
if it's the 60mm marine version they gould use the utility munition (the one used to shot grappels and stuff.
never heard of it...cant find anything on it.
If it does exist, i'd like a link to it because It defies how a mortar operates i.e. inside the tube is a large "firing pin" basically a metal rod as the mortar round slides down the tube it hits the primer on the bottom of the mortar round and ..away she goes...mortars are just like big bullets in how they are fired.
In other words...there is no propellant at the bottom of the "Cannon" or Mortar tube...and the baseball isn't attached to any casing containing a primer and propellant for the firing pin to ignite...so how is the ball going to get fired out of the mortar tube... if they just drop it in the tube it will hit the firing pin...and stay there lodged in the tube.
If the one your talking about contains propellant at the base of the tube and that when ignited causes the ball to fly out...thats not a mortar..its a cannon mortar

If the one you're talking about entails the baseball to be filled with propoellant...thats called a spigot mortar and looks completely different to a standard mortar