The higher rates of firearms suicide among white Americans after the age of 20 hasn't offset this yawning and widening racial gap in death rates linked to gun violence, the figures show.
Firearm deaths have become a major public health problem in the USA: US men can expect to live shorter lives than their peers in many other countries. And while overall US life expectancy increased from 76.8 in 2000 to 78.7 in 2014, it fell for the first time in 50 years in 2015, a trend that continued in 2016.
To try and quantify how much lives in the US might have been shortened by firearms assault and suicide since the turn of the century, and whether certain age groups and black Americans are disproportionately affected, the researchers used data for firearms deaths from 2000 to 2016.
The data came from the Centers for Disease Control and Prevention Wide-ranging Online Data for Epidemiologic Research (WONDER), and were categorised by age group, intent (suicide or assault), and race, and set against national estimates for life expectancy.
Reduced life expectancy usually falls with age, but it dropped suddenly at age 20 for black Americans as a result of being shot and killed, and steadily fell after the age of 20 among white Americans as a result of firearms suicide.
But although the premature shortening of life among whites over the age of 20 was greater than it was among blacks of the same age, this still didn't offset the reduced life expectancy among blacks-a finding that "is indicative of persisting disparities in homicide among younger age groups," say the researchers.
The calculations showed that the overall reduced life expectancy as a result of gun violence was just under 2.5 years, but it was twice as high among black Americans (4.14 years) as it was among white Americans (2.23 years).
Shootings lopped nearly a year off life expectancy in total, but nearly 3.5 years for black Americans compared with under 6 months for whites.
Firearm suicides shortened lives by 1.43 years, but by just over 6 months in black Americans compared with 1.62 years in whites.
The study authors point out that research in 2000 revealed a difference in deaths linked to gun violence between black and white Americans-a trend that has continued-but this gap looks to have widened even further, with the total premature loss of life even greater.
"Our study using cumulative data from 2000 to 2016 demonstrates a total firearm life expectancy loss of 905.2 days, which is nine times greater than observed in 2000, indicating increasing life expectancy loss by year," they write.
The authors acknowledge that the data didn't enable them to look at deaths by ethnicity-Hispanics, for example-and that many ethnic groups may be included in what is understood by black American nationality.
"Americans lose substantial years of life due to firearm injury," write the authors. "In the absence of comprehensive firearms legislation, targeted prevention programmes and policies are needed to mitigate the racial firearm injury gaps in the USA," they conclude.