SpudFiles

I had to re-read that to check that post was actually for this topic

A longer barrel wouldn't work in the same way putting a few more feet of barrel on a coilgun wouldn't work, the propulsion is not anything to do with the barrel, it's only there to guide the projectile.

Hotwired is right, the "barrel" doesn't need to be any longer than twice the width of the projectile, it's not going to affect power or accuracy as long as the muzzle crown is properly cut.