No more deadly than any other bullet.Hmmm Golden Bullets............could be deadly......
Over weight, under strength and too expensive.And a gun out of pure gold would be bad?
which is more dense..gold or lead?
Did you just see "The Last King of Scotland"? I think Idi Amin had a gold-plated AK. Gold bullets would work very well, but obviously they would be ridiculously expensive. There are many gold-plated guns out there. The operative parts, as people have been saying, still need to be steel, but gold-plating is simple, you could even do it yourself.
Tungsten is surpassed only by depleted uranium for high density penetrators, but gold isn't as hard.
DU was 18.1 last time I found a figure - it's used for its pyrophoric properties as much as its density.
(And self-sharpening features IIRC).