Coil gun, not railgun. Common mistake.

The amount of precision you're talking about may not be possible. Probably, manuvering a spacecraft at solar-orbit speeds to pass through a ring would be as difficult or more so than matching orbits with a planet, not to mention the consequences of hitting the ring itself. That's assuming you can find a way to hold the rings precisely where they need to be without them going into orbit around the planets or the sun, as the case may be.

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
"The Mayan symbol for "book" looks a lot like a triple hamburger, but I've never seen them claiming it as proof the Mayans had Big Macs." - KaiYeves
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort