Benefit: Your melee and ranged attacks count as magic for the purposes of bypassing damage reduction and other situations, such as attacking incorporeal creatures.
A gun requires a roll to hit. The ability doesn't say that it stops you from needing to hit, so it doesn't alter how you hit.
ALL it does is count as magic for DR and incorporeal creatures. This isn't a great ability for a gun (which can be made magic with a cheap 140 credit fusion) but is more for punching ghosts in the face.