Railgun technology, a popular concept in science fiction, is achievable in real life but is still far from being widely spread. One amateur inventor from the US decided to make a huge step forward: He has built a portable self-loading railgun and uploaded footage of his tests to YouTube for the rest of the world to see.
Instead of using explosives or a propellant, the weapon uses electromagnetic force to launch high-velocity projectiles by means of a sliding armature that is accelerated along a pair of rails.
As follows from the description of the video, where the enthusiast can be seen shooting at a melon, his SR-1 railgun is capable of firing 6x19 mm armatures.
It takes just 15-30 seconds to recharge the batteries of the "field augmented circular bore plasma armature railgun." While the structure is made from mostly 3D printed components, the entire system weighs less than 30 pounds (13.6 kg). According to its developer, the SR-1 can be fired in single shot mode or semi-automatic mode.