You never know. With advanced-enough technology and enough moving parts, anything is possible. While it could never work in modern designs, they might have a very sophisticated way to transfer the shots from the mag to the barrel. For handcannons, while overly complicated, the hammer could trigger a small reaction within the gun that propels the projectiles forward. At the end of the day, it's best to just fall into the side of space magic. Even if it's not currently viable in real life, I would prefer they design the weapons to look good. At the end of the day it's a game, it does not matter how realistic they look. They could have coded a rock to shoot bullets, realism is not needed.