I made a test and filmed it and figured I would share my results. Disclaimer, this is not an incredibly scientific test, as u will see shortly.

Setup: bought a 100 ft taper measure, took it to my practice area and took a measurement. I found out I was slightly off by using google maps and the distance between myself and my target (this time the wall next to the boards in the video) was actually 21.9 meters instead of 20 meters. I then picked out a stone of football shape and weighed it to be about 125 grams. This was my first projectile. The next 3 projectiles are 1 inch steel balls each weighing about 66.3 grams. The resulting energies and velocities are in the description but I'll post them here too:

First projectile slung is a 120-130gram stone, all the rest were 1 inch 66gram steel balls.

Velocities measured with camera frames, with the distance between myself and the wall being 72 feet (21.9 meters(measured with a 100ft measuring tape, no google earth this time)).

the stone:39m/s = 70ft lbs = 95 joules

1st steel ball: unknown, hit board and is too difficult to find exact frame with moderate accuracy, however it did bust right through it, which is a 3/4 inch Sande plywood board.

2nd steel ball:46m/s = 52ft lbs = 70 joules

3rd steel ball: 45m/s = 50ft lbs = 68 joules

For reference, 550 grain arrows launched from a 40lb recurve at a 30 inch draw with a velocity of 143fps has the following energies:43.5m/s = 25 ft lbs = 34 joules

a 40 grain .22lr out of a pocket pistole with a velocity of 730 fps has the following energies:222.5m/s = 47ft lbs = 64 joules.

https://youtu.be/K_iAslRZwlQ