MeowersRebecca HailAmata LireinFriendly reminder: Space, contrary to popular believe, is not a vacuum. Lots of hydrogen and deuterium out there, and depending on where you are in space its density differs. So in the long run a projectile will slow down to a stop... it would take faaaar longer then the game suggests though
Gravitational drag might be a bigger factor in slowing down projectiles. Density in the interstellar medium varies but 30% - 70% of it have a density of 10^-4 to 10^−2. It's well possible that a reasonably sized projectile might not be stopped by friction until after the end of our universe.
Pretty much chance for that projectile to end up falling on a star. Unlikely it'll have much speed to escape the star's gravity completely, and, if "combat zone" have it's own relative orbit speed (depends on closer bodies, etc...), then projectile, fired somewhere to the "retrograde" direction, have a chance to end up that way... After several millenias...
Well, in Mass Effect for instance the spinal main guns of the human battleships fire 20kg iron projectiles with a speed of 3-4% of the speed of light. The escape velocity for the sun is 617km/s, so I would guess that a misshot would manage it to leave the system unless it impacts on some orbital body.
For the guns in Elite, yeah. They have nowhere enough energy to make their projectile escape the gravity of a star.