https://rutube.ru/video/a0595b665831a3f29c778d46fc85700c/

Sand balls for throwing from a sling. I continue to develop sports equipment for slingshot throwing. The task is to make a projectile for throwing at longer distances on sports hard targets. 2- and 3-zone. Since tennis balls at distances of more than 12-13 meters begin to plan strongly and lose their speed, there is a need for projectiles that fly further and more evenly. Sandbags are used in the video. The diameter of the shells is from 50 to 52 mm. The average weight is 90 grams. the discrepancy is from 85 to 95 grams. This weight is much easier to control when throwing than 55 grams of a tennis ball. The accuracy is better and the flight of the ball is more predictable than that of a tennis ball. The sand inside the balls has been sifted, and all hard fractions of more than 3 mm have been removed from it. From above there are 10-15 layers of plastic film (old bags), the film holds sand well. Next, I make a rounded shape with tape. Then I put a round ball of sand and film in a cloth shell. Despite the imperfect round shape of these balls, they fly better than perfectly round tennis balls.

Thanks, I'll look at the links. It's very interesting how Jagur did it. On soft targets, my balls retain their geometry. But if you hit a hard shield, I think the geometry will also go away. I still have this experiment ahead of me