Sounds like a good concept, the shell wouldn't do too much damage to a non helmeted
player, but in the event of a parachute malfunction getting struck by a AI grenade falling from the sky would suck.
I know alot of players that refuse to wear helmets for many reasons, having artillery lob anything larger than tennis balls is a bad ideal in my books.
Maybe a future ideal would simply be Shell that would come apart and rain bbs earthwards. The 2 part shell is a great ideal Ethier a very simple weighted noise piece that comes apart when the projectile starts it ascent earthward, or a shell using a tilt switch and solenoid to seperate the shell.
I am no engineer, so I'll just leave my 2cents out to others with more formal technical training to nitpick at.