Doesn't seem right. Put the current total and assume it will remain static (which isn't true at all as it has been declining), remove suicides, as that isn't you "being shot dead" but rather you "shooting yourself dead" and you get about 10k deaths a year. Lets round it up to 15k. Assume 300 million people in America also won't change. That puts you at .005%. Now lets assume humans live inordinately long lifespans of 100 years. .5%
So half a percentage of americans, assuming a higher than normal gun death rate that doesn't decline, in a population that doesn't increase, and an extremely long life span will be killed by guns. Now, that is just removing suicide, so it does also include people being shot dead by the police for legitimate reasons, which should really be removed, but I don't have statistics for that handy.
So realistically, it is under one half of one percent. And your chances of being in that group are dramatically lower if you aren't a criminal, don't hunt, and don't cheat on your spouse.