It there was no conviction of the felony than there is no conviction, however you should disclose everything, every detail to the background investigator. He's going to look into everything and he'll find out one way or another. It would look very bad if he found this out when you should have told him. The very fact you were charged will look bad, however if there is no felony conviction then it's not an auto DQ. A LEO will be along shortly to give a more detailed explaination.
"...Our natural, inalienable rights are now considered to be a dispensation of government, and freedom has never been so fragile, so close to slipping from our grasp as it is at this moment.” Ronald Reagan
"Those who beat their weapons into plows will be plowing for those who don't."