system
Given the following post, respond as if you're commenting on Reddit:
human
[General] What's the SciFi equivalent to the M2 machine gun?

It's as close to mechanically perfect as you can get. In over a century of constant use, the only improvements that have been made is a quick change barrel and improved ergonomics on the grip.

What other weapons in science fiction have been used for centuries with no significant changes because they are ideal for their purpose?
gpt
The Lasgun from warhammer 40k, the most basic weapon used by the most basic soldiers of the imperium. Quintillions of guardsmen have used lasguns over 10k years, and since he imperium hate inventing things the weapon never really changed.