we had those for animal control when I was an MP in the Army. I qualified with one but never darted an animal. I don't remember the things ever leaving the arms room other than for qualification. In order for me to use one it had to be approved by the provost marshal, then the weight of the animal had to be estimated, Then a vet had to prepare the dosage. The gun had to be picked up at the arms room and then if the animal had not died of old age we could dart it.