I have seen a video of a guy with a fuckin real handheld railgun. What was that? How do handheld railguns work? How can you store the energy for that?
A "handheld railgun" is a type of firearm that uses a linear accelerator to propel projectiles. These guns are typically used in military and law enforcement applications, but they have also been developed for use in recreational shooting.

In a hand-held railgun, a high voltage electrical current is passed through a conductive wire (usually made from copper or aluminum) to create an electric field that accelerates a projectile along the length of the gun. The acceleration force generated by the electric field is then transferred to the projectile via the wire, causing it to be fired out of the muzzle at high speed.

The basic operating principle of a hand-held railgun is similar to that of a traditional artillery shell, where the explosive force of the shell is produced by the rapid expansion of gases inside the shell as it travels down the barrel. However, unlike traditional artillery shells, which are launched from large fixed weapons, hand-held railguns are designed to be portable and easily operated by one person. This makes them ideal for use in situations where troops need to fire quickly and without having to rely on heavy equipment.

To store the energy required to launch a projectile using a hand-held railgun, a battery is usually used to provide the necessary power. The battery is connected to the gun's electrical system and charged before being used. During operation, the stored electricity is released through the conductive wire, creating an electric field that drives the projectile forward.

While hand-held railguns offer several advantages over traditional artillery systems, they also present some challenges related to their size, weight, and complexity. Additionally, the technology behind these guns is still evolving, so there may be future improvements and modifications that could further improve their performance and capabilities.