Someone, somewhere has to still use slug throwers.

But they shouldn't look exactly like specific models of Earth slug throwers.

"A long time ago in a galaxy far, far away..."

The issue isn't that they have slug throwers, it's that they have AKs.

Firearms in Star Wars could be very cool to see, if done in an interesting way. AKs are a deal breaker though. Either makes something that looks cobbled together, something like a Luty or a Sten (not identical, just along those lines); or something that looks archaic, perhaps an old-school revolver-style gun; or a gun that looks more advanced than most current firearms, like the mentioned XM8 or FS2000 (although, again, not identical.) I think the last one could be interesting, and would fit. In a setting where they'd advanced from projectile launchers to lasers, the 'old, funky, and outdated' projectile launchers would still look more advanced than our current guns, most likely. So I'd say a super advanced but beat up looking firearm would be interesting and fit the theme.