Thing is, there is a planet sized computer base. Mercury. Which means the vex are the creation of Rasputin. Then they are sent back in time to create new data bases for him on the planets. This creates loops in time that are side by side and explain how the stranger has the ability to come here. The rifle isn't from the future, but from a loop farther into the coil, where Rasputin gets more planets under his control, and the technology is more advanced.