A needle is the better way to do it regardless of what gauge is involved. Guns have many small parts that can never be entirely properly sterilized.
To be frank, you shouldn't get your ears pierced with a gun to begin with, not to sound mean.
you would have to special order piercing earrings at a 14g in order to do it by gun because otherwise average size piercing earrings that they use are an 18g
Get your doctor to do it. It isn't uncommon to see piercings done at malls get infected, and that can make you very sick. be careful!
