Doctors kill more people than guns do.
And if doctors want to save more lives than are lost to gun violence all they need to do is reduce their error rates by around 10%. No need to be perfect, just improve their work quality by a small amount.
Of course they could do even more if they focused on mental health, and avoided prescribing lucrative pain relief drugs that lead to addiction and the crime and violence associated with it. If they really wanted to save lives they could educate people so that abortion was as rare as possible, and they could work to end inner city gang related culture.