I've always thought parachute rounds were one of the "great challenges" remaining in spudding. I would love to have a parachute round!
It really should be possible to launch the round up a few hundred feet before the chute deploys. This requires an actual chute release mechanism and not just a parachute wrapped around a weight. It probably also requires an areodynamic round so the thing isn't tumbling like crazy when the chute deploys.
The water rocket folks have several nice mechanisms for deploying a parachute. (Google "water rocket" parachute "tomy timer" "air flap" ...) Their solutions deploy the parachute near apoge (highest point in the flight). The problem I've had is trying to get their solutions into a 2" barrel. Of course you could use a custom gun with a big diameter barrel but I think a round that worked in a standard barrel would be cool.
The only solution I've been able to come up with (but haven't actually tried) is to essentially mount the parachute equiped "water rocket" on a long rod that fits into the spud gun's barrel. The "water rocket" isn't a rocket, just the payload / parachute carrier / deployment mechanism in an aerodynamic package. The loaded round actually sits at the end of the barrel and is launched with a sabot.