Congrats, you successfully got shot with molten metal instead of regular metal.

It would melt it, spraying the wielder with molten metal.

Not positive on the actual physics but in universe they can't block the slugs, the metal just gets superheated and goes through the lightsaber

There was a sith, former apprentice of Vader in the good canon version that used a weapon that was like a cat o nine tails but it used both energy and normal metal components and jedi had a very hard time dealing with it, other than Luke, which the good canon had progress into a powerful Jedi that could even force project an image of himself without dying, but also valued his friendships and connections and didn't briefly consider killing his own nephew and would have never fucking gone into hiding as a hermit instead of dealing with the problem he created.

Anyways, this devolved a bit into a fuck Disney rant, but the point was that someone using a weapon that combined lightsabre blades with metal blades was extremely effective against jedi just using lightsabres. Luke could only handle her because he was a beast with and without a lightsabre.

Not sure what the canon says, but it really seems like blaster bolts travel considerably more slowly than a high power rifle bullet, so I'd still pick the slug thrower.