Back in the late '80's and 90's I was heavily involved in training and field trailing English Springer Spaniels. We needed pigeons, lots of pigeons, for dog training. We used a "cannon net" to catch whole flocks of the birds.
A mechinist friend made us four cannons for shooting the heavy net over the birds as they ate at our large bait piles of corn and other grain.
The cannon barrels were made of 3 inch steel pipe, 2 feet long. A breechplug was welded into one end, and a touchhole was drilled into the back of the breechplug. The touchholes were made so a 12 guage shotgun shell would fit up inside it. The 12 ga. shells were loaded with 150 grains of 2F blackpowder. Instead of a primer, we rigged an electric wire to fit in the primer hole. All four cannons were linked together on the same electrical wire circuit.
Our cannon balls were old pistons that closely fit the pipe diameter. A rope was tied onto the piston where the rod would normally be. The other end of the rope was tied to our net. The pistons were then rammed down the barrel.
With the four cannons spread about 10 feet apart, braced in the ground, and the pistons rammed home, but connected to the net which was neatly folded in a line along the front of the cannons, bait spread on the ground near the net, and we were ready.
All we had to do was touch the ends of our electric wire to our truck battery terminals, and BOOM!
It worked great, and we caught hundreds of pigeons with just one shot.
We did this at a grain elevator in Saginaw, MI. We always set up our net so that the cannon fired toward the Saginaw River, just in case any of our cannon ball pistons should break loose.