User blog comment:Rozh/Surface-to-Orbit Artillery/@comment-131756-20110321005343/@comment-923138-20110321041619

Well, that seems like the basic property of how a coilgun works. Projectile is held in place, you charge the magnetic coils, the slug is fired, and as it travels through the tube the coils activate one after the other to accelerate it. So from what from it looks like, the recoil would come just from the primary combustion, since the bulk of the slugs speed comes later from the coils, which shouldn't produce recoil. Of course, it's possible there is no combustion and the slugs are initially launched from the same magnetic pull, but I guessed combustion since we see what looks like a visible explosion around the barrel's rim. That would also make for no recoil. For the acceleration bit here's