I am a high-school student of the sophomore year and I have a project which is I want to make a coil gun that is 3 stages and I want all three coils to each be powered by its own capacitor. I want to specifically know how to time each coil which i would find more precise than an IR system(if i'm wrong please correct me) the coils will be about 2-1/2 to 3 inches apart(if there is a better way to space them tell me) and my projectiles will be 6 mm .89 gram steel bullets. I'm open to suggestions. I have limited funds but have access to drafting software and basic soldering and electronics skills but my knowledge is limited.

Welcome here!

 

IR for infrared? It can be quick. I'd prefer a position detector over a timing, because you can't predict accurately how strongly the projectile accelerates.

 

"Basic soldering and electronics skills" would be a very serious limitation for this project. A coil gun is full of less-than-trivial electromagnetism and power electronics.