From the ArcaMax Publishing, Jokes Newsletter:
http://www.arcamax.com/news/jokes/s-368088-969836
A communication technician drafted by the army was at a firing range.
At the range, he was given some instruction, a rifle and 50 rounds. He
fired several shots at the target. The report came from the target
area that all attempts had completely missed the target.
The technician looked at his weapon, and then at the target. He looked
at the weapon again, and then at the target again. He then put his
finger over the end of the rifle barrel and squeezed the trigger with
his other hand. The end of his finger was blown off, whereupon he
yelled toward the target area: "It's leaving here just fine, the
trouble must be at your end!"