i was fairly certain the HL stood for heavy laser...
anyhow, lasers or not...what would their muzzle-flash look like? maybe these things are shooting black-eye-peas that are irradiated and juiced out of a strainer at the speed of sound....it's gonna look different than a gun firing....ya have to take into account the vacuum of space too
a muzzle flash is flame and fire from the explosion of the powder in a bullet, propelling that bullet out of the chamber and barrel
provided a gun had the air to fire the bullet in the first place (you need oxygen for combustion), i'm not too sure if there would be enough air in the vacuum of space to have a muzzle-fllash at all
so...taking that into consideration for solid-projectile-type guns, i'm curious as to what psuedo-science has to say about what a muzzle flash would look like from a colored-light shooter