new guns have the advantage of not having anything wrong with them (lemons excused) but come with a gun+hicap+cheapo battery+cheapo charger
used guns run the risk of breaking quickly, but most of the time come upgraded, and with a bunch of extras.
usually boils down to price and package
"You know what the chain of command is? It's the chain I go get and beat you with 'til ya understand who's in ruttin' command here."