To do this experiment you a need powerful disc shape magnet with a hole and smaller disc shape magnet for the tip of the projectile. The smaller magnet should be tightly secured to the tip of the projectile so some glue is recommended. I used an aluminum tube which I shouldn't because the induced eddy currents slows it down little bit.
Step 1: Measurements
Big magnet: Ø 60 mm x 15 mm, Ø 15 mm hole in neodymium / 8 Ø mm hole in the metal casing, grade N35, 100 kg pull force
Smaller magnet in the launcher: Ø 32 mm x 8 mm, Ø 6 mm hole, 13 kg pull force
Projectile: Aluminium tube = Ø 5 mm x 80 mm.
There are three ring magnets in the projectile, 1 Magnet = Ø 10mm x 3 mm, grade N50
Whole weight of projectile is 6,9 g
The steel casing of the big magnet is crucial for this experiment because the projectile magnets lock to the steel.
All of the magnets in the launcher as well as in the projectiles are the same polarity