I was thinking about an airsoft mortar and i saw a lot of peoples ideas and they were really complex and it required fuses, fins, bottles, CO2 and pyrotechnics
and i thought...
maybe it doesn't have to be so complicated
so what i was thinking is
if you buy one of those $2 fireworks that shoot a shell up into the air and just make a loud noise, ("airbombs") and fill it with some 50-100 bb's
you have a mortar shell right there
then you can light it and drop it into a pipe that's about 1 inch in diameter
that way when the firework shoots the bbs and the exploding shell with it, the exploding shell explodes and scatters the bbs and could have an pretty good area effect
iam guessing
it should be safe...
as long as you don't shoot it at people
but then again a mortar doesnt shoot directly at a target
and you probably shouldnt use it in wooded areas
P.S. Canada Day is on July 1st or something so pick up some fireworks