What’s the current state of railgun development? The US Army began this country’s long-term experimental railgun program in 1980. In 2010, the United States Navy tested a BAE Systems-designed railgun for ship emplacement. It accelerated a 3.2 kg (7pound) projectile to 3,390 m/s, or about Mach 10. The non-explosive round carried18.4 megajoules of kinetic energy. For comparison, a single stick of dynamite produces about 2.1 megajoules of energy.
     Rail guns were pursued because of their perceived lower operating cost than conventional ballistic weapons. The absence of explosive propellants and warheads to store and handle, as well as the low cost of non- or low explosive projectiles compared to conventional weaponry made them attractive to planners.
     But the project was abandoned. An electric arc forms between the rails and the projectile (or the armature that pushes a non-ferromagnetic projectile). The rails eroded so quickly that their frequent replacement made the gun impractical.
     Like the plasma cannons and laser cannons I examined previously, rail guns developed for military application are enormous devices with unwieldy power sources. However, low power, small scale railguns are popular college and amateur projects. But the main obstacle to a military application remains high rail erosion and frequent rail replacement. Bummer.
     But there is another electromagnetic acceleration device. Unlike railguns, coilguns use a series of electromagnetic coils to sequentially energize and propel a projectile through them. For ferromagnetic projectiles, a single-stage coil gun can be formed by a coil of wire, an electromagnet, and a ferromagnetic projectile placed at one of its ends. This design is like solenoids used in electric door locks commonly found in most commercial buildings, or the electric valves used to turn your lawn sprinklers on and off.
     Power is supplied to the electromagnet from a fast discharge storage device, typically a battery, or capacitor(one per electromagnet). Many hobbyists build coilguns, using off-the-shelf capacitors, and low inductance coils to propel the projectile forward.
     An Arizona-based company called Arcflash Labs sells a coilgun rifle. The GR-1 Anvil ® fires 30-gram steel slugs at up to75 m/s with a muzzle energy of about 85 joules. That’s comparable to a pneumatic air rifle. The muzzle velocity of a typical rubber bullet generally falls between 60 m/s and 80 m/s. The Anvil ® firing rate is up to 100 rounds per minute, and it comes with a 10 round magazine. The rifle weighs 20 lbs. For comparison, a 30-06 hunting rifle weighs 5-8 lbs. An AR-15 weighs 6 or7 lbs.

Below: Photo by Arcflash Labs

     Despite the higher projectile velocities a railgun can achieve, coilgun weapons have been commercialized first. Unlike a railgun, coilguns place an actual barrel inside the magnetic coils, eliminating wear and tear. Their durability means less maintenance and repair.
     Coilguns are suitable for crowd control in a security setting. Improvements like solid state batteries and lighter capacitor materials over the next forty-plus years should reduce their weight comparable to a military rifle’s. It’s conceivable, miniaturization could result in a sidearm with comparable specs to today’s GR-1 ®.
     I don’t foresee muzzle velocities increasing enough to match the 1000 m/s of an AR-15. But if I’m wrong about that, then the same rifle could switch between crowd control and lethal settings—although the higher muzzle velocities would likely be restricted to outdoor use. A high velocity round ricocheting off the walls inside Ep City could have nasty unintended consequences, whether it be striking innocent bystanders, sensitive life support equipment or airlocks.
     It's taken three months, but I finally have a useful crowd control weapon for a city of 100,000 on Mars in the latter half of this century. Watch for its deployment in my new book, Wetware, coming out later this summer.

     Like what you just read? Share this issue with friends and encourage them to subscribe to receive free short stories, news about upcoming promotions and books by yours truly and other exciting Sci-Fi authors!

For further reading
https://en.wikipedia.org/wiki/Railgun
https://www.quora.com/How-many-joules-does-a-Bazooka-or-a-RPG-rocket-produce-upon-impact
https://en.wikipedia.org/wiki/Coilgun
https://en.wikipedia.org/wiki/GR-1_%22Anvil%22
https://arcflashlabs.com/product/gr-1-anvil/
https://www.researchgate.net/publication/239761536_Design_and_Implementation_of_High_Efficiency_High_Power_Density_Front-End_Converter_for_High_Voltage_Capacitor_Charger