I see there is a specific adjustable skill for Non-projectile, Projectile, and Heavy Projectile Weapons...What skill does Explosives and Thrown Weapons use?
Combat rules haven't been written, so there is no official answer. Various people have put forth various suggestions, however, usually involving a combination of skills.
____________
I dare you to make less sense.
Are you a newbie, or do you have access to newbies?