For your convenience: Page 63
Here's a little lowdown now that I don't have a little black bar to type in: The Gauss Rifle, also known as a coilgun, uses a coil of charged magnets to propel projectiles forward. They are more energy efficient and far easier to build in smaller scale than the railgun, which uses two rails of electromagnets to propel projectiles forward. Considering the ammunition for both weapons is usually made of nothing but solid nickel-iron, it's no surprise why the ion trails of both weapons are so similar, and why Jake was misled this whole time in his life.
Fun Fact: Gauss was a German scientist who studied electromagnets, hence why his name somehow got stuck on the coilgun.
Science fiction weapons are so cool. (I take that back. These weapons actually exist. Just not in mass production yet.)