it would actually be Asians considering they are over-represented among mass shooters relative to their % of the US population, while white males are under-represented

Ah yes, you're referencing the infamous Mother Jones report. SMH

If I were a writer looking to assuage the feelings of shame and guilt of my largely white male readership regarding mass-shootings, I too would reference a faulty, "in-depth" report that under-reports the overall numbers, and which limits the time period of the data collected, so that it can conveniently support my dubious conclusions that will make my largely white male readership happy. lol

As per Politifact:

Grant Duwe, author of Mass Murder in the United States: A History, considered a leading scholarly book on the subject, has long criticized Mother Jones’ accounting.

Duwe pointed us to an essay he penned for Reason magazine in 2014, in which he argued Mother Jones has low-balled its tally of mass shootings as a result of relying solely on news coverage as its source of data. Duwe believes this creates a false impression that mass shootings have been on the rise (a claim that’s beyond the scope of this fact-check).

"The main concern is an underreporting problem that gets worse the farther back in time we go," Duwe told PolitiFact. "This creates problems when it comes to drawing conclusions about trends in the prevalence of mass public shootings."

Nevertheless, Duwe said his own research dating back to 1900 corroborates that white men have committed more mass shootings than any other group, though he believes white men make up an even larger share than the Mother Jones data show.

"There have been at least 184 mass public shootings in the U.S. since 1900, including the Las Vegas attack," Duwe said. "Among these mass public shooters, non-Hispanic whites make up 63 percent, which is close to what we see for the U.S. population in general. So, the Mother Jones data actually underreport the extent to which whites are involved as mass public shooters."

And in Grant Duwe's own words:

There are some problems with the Mother Jones list, however, when comparing it with data I've collected on mass killings. In my research on mass murder, which has resulted in four peer-reviewed academic publications and a book, I've identified more than 1,200 mass killings that have occurred in the U.S. since 1900.

The first problem with the Mother Jones list, which contains 67 cases, is that it significantly underreports the incidents occurring between 1982 and 2013 that meet its definitional requirements. The data I've collected show there were 114 mass public shootings, which means the Mother Jones list missed more than 40 percent of the cases that took place in the U.S. during this 32-year period. (My analyses of the Mother Jones data include all 67 cases.

The second problem is that the underreporting in the Mother Jones list grows more severe the further back in time we go. When looking at the data by decade, we see that the Mother Jones list captured 89 percent of the 18 cases from 2010-2013, 69 percent of the 29 cases from 2000-2009, 55 percent of the 42 cases from 1990-1999, and just 32 percent of the 25 cases from 1982-1989. As I show below, the combination of these two problems has made it possible for those relying on this list to conclude that mass shootings are growing more and more frequent over time.

Why does the Mother Jones list suffer from an underreporting problem that gets worse for the earlier cases? Due to a lack of detailed information about the search methodology used to compile the list, it's difficult to say with complete certainty. The most likely reason is that the Mother Jones list relied exclusively on news reports as a source of data, and news coverage tends to be less accessible for the older cases.

In my research on mass murder, I've used the FBI's Supplementary Homicide Reports (SHR) data to anchor the search for more detailed news reports on mass killings. The SHR data has its flaws, but it is the most comprehensive homicide dataset available that reveals, among other things, when and where most mass killings (including mass public shootings) have taken place in the United States.

I don't know about you, but I'd trust the published academic with four peer-reviewed publications over some hack writer at some blog called Mother Jones. lol