Appears to be mostly honest, for example does not count as "teens" those over 17, but it doesn't capture the by far highest fraction of defense gun uses, those in which the weapon is never fired (over 85%, maybe over 90%; as they say, they don't re). On the other hand:

"While CDC utilizes death certificates for gun deaths, they, and the FBI rely on a sampling of sources and extrapolate those numbers to provide aggregate totals that reflect the calculations within their methodologies."

Is I believe flatly false for the CDC, they tally what the death certificates say and report numbers down to single digit precision, which I wouldn't expect from extrapolations. While the CDC for example does make estimates for flu morbidity and mortality, this posture by the site allows them to avoid reporting the remarkable figures on steadily decreasing fatal gun accidents, now down to 486 as of 2019, from 1955 in 1980.

That's during a period when the total population of the US increased by about half, gun ownership became much more widespread due to the nationwide sweep of concealed carry laws to 43 states and 74% of the population, which includes the number of guns owner by the population over doubling. US gun culture is deadly serious, shall I say, about safety.