There are many ways to create sci-fi texture sounds. You will need to know how to use synthesizers as well as know how and lots of inspiration.

A sound of future weapon should consist of several layers:

• loading gun sound,
• a sound of metallic parts
• the impact sound of the shot
• It could also have a sound when a gun cools down after shooting plasma
• echo sound

You can synthesize each layer separately. Some textures are created when you manipulate effects chain. Listen to how interesting these sounds can be.