One of the things that was occasionally done was to inflate something very large, like a weather balloon, and drop it over the side. It could then be used as a target at longer ranges.
So one day, a ship I was riding on did that. I was riding it to conduct and observe some tests. Since the ship was independently transiting, I didn't have much to do, so I went topside to watch the shooting.
One of the weapons that the sailors were shooting at the balloon was a M-79 "Bloopergun".
They were firing blue rounds. The balloon was off the starboard side at maybe 300 yards or so and the ship was steaming around the balloon in sort of a lazy circle. Most of the sailors were missing to the left of the balloon.
I said something to one of my fellow shipriders along the lines of: "That thing is a big as a barn and they can't hit it."
The gunner's mate senior chief must have overheard me, for he spun around, fixed me with his patented Goat Locker Stare and said: "Maybe you'd like to give it a try, Ma'am."
"Thank you, Senior Chief, I'd like that." So I went over there and he gave me a fifteen second checkout on the controls of the M-79. I checked to make sure that the windage adjustment was centered, then I shouldered the weapon, aimed and fired.
The dummy warhead splashed right in front of the balloon. The senior chief's jaw dropped and he said something along the lines of: "Goddammit, Lieutenant, how'd you do that?"
"Easy," I said, as I handed the Bloopergun back to him. "The balloon isn't moving, the ship is. So you gotta lag the target, not lead it."
Don't ask me about recoil, I don't remember it kicking that much. What I should have done, though, was to ask for the cartridge case as a souvenir, and I didn't do that.
 Never you mind what kind of tests. If I were to tell you, I really would have to kill you.
 The projectiles were inert.