Allow me to put my Gun-Nut Hat aside, and don my Star Wars Fanboy Fedora.
lugthrowers were considered by many to be a primitive, inferior technology when compared against blasters, and were often used by those without access to better weapons, such as primitive cultures. However, they remained popular for the unique advantages they offered. For example, during the days of the Galactic Republic, mercenaries fearing an intervention by Jedi Knights used rapid-fire slugthrowers that were impossible to deflect unlike blaster bolts. They were also popular amongst forces looking to take advantage of the explosive nature for intimidation or to ensure destruction. Whatever they lacked in functionality, they regained in stealth. A slugthrower could be silenced, while a blaster could not. Also, blaster rounds were almost always visible. Although this could be seen as an advantage, non-tracer rounds used by slugthrowers added an extra element of confusion and surprise, not allowing the target to see where the shots are coming from. Furthermore, slugthrowers were generally cheap and easily repaired. In addition, the projectile itself could have unique properties. Explosive, pyro and mercy slugs each had different effects. Explosive ammo dealt additional kinetic damage to a target. Pyro ammunition could cause burns that were as dangerous as the projectile, or set items on fire. Mercy bullets made of rubber or semi-rigid plastic gave a way to set a slugthrower on 'stun'. Of course, this meant carrying extra ammo or magazines - and special rounds are costlier and rarer than conventional slugs. Bounty hunters that carried slugthrowers tended to make extensive use of special ammo in their work. Some mix rounds in the same magazine, starting with mercy bullets and working their way up to more lethal types in case the less deadly projectiles fail to stop their opponent.
The abilty of Jedi to deflect or block slugthrower rounds has varied over the years. Lucasfilm has offically stated that licesned materials (comics, novel, roleplaying games) are all cannon. The movies never address the question of "What caliber for Jedi?" but the RPGs have... and its changed over the years. Currently, Jedi can block them but they can not redirect them (the lightsabre melts the bullet.)
