The study controlled for literally dozens of other factors, including
criminality and illicit drugs. Furthermore the extra homicide risk
associated with firearm ownership was not from shootouts between drug
dealers or gangs, but domestic homicides.

Dr. Paul Blackman writes:

No. The study measured about 2.5 dozen items, but controlled for about
six — with a number of items prevented from measurement by matching
the controls (race, age group, sex, etc.)

All right. They controlled for four factors by matching and another
six in the multivariate analysis. The other 2 dozen measured items
could have been controlled for if they had proved to be statistically
significant.

None of the items measured
or controlled for involved drug trafficking, as opposed to simple drug
use.

Though you would expect this to be strongly correlated with arrested
and with drug use.

One would certainly have expected a higher-than-average rate of
domestic homicide when the three-fourths-plus of homicides outside the
home were excluded — although non-gun and domestic homicides were also
minimized a bit by excluding the slayings of pre-adolescents in the
home.

Yes, the fraction of homicides that were domestic would be higher than
for homicides in general, but that wasn’t my point. The “extra”
homicides associated with gun ownership weren’t from drug dealers
shooting each other but domestic ones. That is, the alternative
explanation: “Drug dealers own lots of guns and are likely to killed
by other criminals” does not fit the data.