Projectile Launcher Advanced. This durable Projectile Launcher, of aluminium construction with hardened steel latches, has string release trigger mechanism with bore sights and pivots from horizontal to 90°. It comes with 19mm diameter ball which is easy to place in the launch position. Trajectories vary less than cm because the ball does not spin when launched. The apparatus includes an assembled spring loaded gun, two balls of aluminium, an integral protractor and plumb line and comes complete with operating instructions. Weight: 1.74kg. Dimensions (L W H): 40 10 18cm.