A few other observations.
Gender, Geography and Religion
Gender (as it intersects with race)
The Pew study controls for many other factors, but not for gender. Military veterans are overwhelmingly male (about 92%). There is a strong gender divide between men and women on overall liberal to conservative political inclinations at this time. Consider, for example, this hypothetical election map based upon polling results:
The political divide is likely to be even greater among veterans than the general public, because female veterans are disproportionately non-white relative to active duty service members as a whole, and non-white women tend to lean more strongly to the political left than white women, white men, or non-white men.
An October 2018 survey from the Military Times (whose readership and samples skew towards more senior soldiers who are more politically engaged and conservative than the military as a whole) confirms this trend:
Also, women who join the military are engaged in an act contrary to traditional gender roles that is often considered feminist, while me who join the military are affirming traditional gender roles which tends to be an act that leans conservative.
The Pew study does not note the fact that "Red states" in which the general population is more conservative overall, accounts for a disproportionately large share of volunteer military recruits, especially among soldiers who are white. This influences the politics of soldiers, and in turn, of veterans. (New Mexico and Utah are exceptions that prove the rule.)
Furthermore, and not independent of the geography issue, active duty military service people are about twice as likely to be Evangelical Christians as the general public.
In rough numbers, one-third of American Christians are Protestants who belong to mainline Christian denominations described by the military for purposes of assigning its chaplains as "liturgical Christians" such as Episcopalians, Lutherans, Presbyterians and Methodists, about one-third are Roman Catholics, and about one-third of American Christians are "non-liturgical Christians" by the U.S. military which are predominantly members of Evangelical Christian denominations such as Baptists and Pentecostals.
But among active duty service members, there are about five non-liturgical Christians for every two liturgical Christian, even though the numbers are roughly even in the general population.
Specifically, the divide between the Evangelical Protestants (a.k.a. "low church Protestants") and the "liturgical" Protestants, based upon data from a lawsuit in the late 1990s revealed that 15% of service members are liturgical Protestants, 41% are non-liturgical Protestants, 24% are Catholic and most of the rest do not have a religious affiliation.
Non-liturgical Christians are among the most reliably Republican and conservative demographics in the United States.
For what it is worth, the Air Force Academy, which produces a significant share of Air Force officers, is somewhat less skewed in this regard and has a much larger share of religious non-Christians than the other military services, possibly because service enlistment is significantly influenced by family history and families with a long history of military service in multiple generations, by definition largely lack a history of Air Force service.
Subtypes of Military Veterans
It is worth observing that there are at least three subgroups of veterans with distinct ideological profiles.
For example, the blog 538 reported in 2009 that:
about two-thirds of majors and higher-ranking officers identify as
conservative, as previous studies found. But that tilt becomes far
less pronounced when you expand the pool of respondents. That is
because only 32 percent of the Army’s enlisted soldiers consider
themselves conservative, while 23 percent identify as liberal and the
remaining 45 percent are self-described moderates. These numbers
closely mirror the ideological predilections of the civilian
Very few military officers identify as "liberal" and the balance identify as "moderate".
Most living military veterans who were not military officers who served prior to the of the draft on July 1, 1973 were conscripts who did not volunteer for the military. A typical age at conscription was 20 years old. So, most living military veterans who were not military officers born in 1953 or earlier (i.e. age 67 or older) were conscripts.
Conscripts have historically been almost identical politically to the general population with the same age, gender, education, race, etc., despite the fact that select groups on the left (conscientious objectors) and the right (clergy) were exempted from service.
Surveys of active duty service members in the U.S. military who enlisted voluntarily have consistently shown only a slight deviation to the political right from demographically similar members of the general public.
The partisan skew of enlisted volunteers tends to be slightly more centrist in times of widespread patriotic military enlistment, such as following the 9-11 attacks, and slightly more right leaning in ordinary times.
Currently, about one in six active duty military personnel are commissioned officers, and historically, the percentage has been a bit lower (there is a somewhat higher percentage in the Air Force proportionately and a bit lower percentage in the Marines).
Historically, surveys have shown that 80%-90% of military officers are Republicans, and the skew is even greater among white male military officers who make up a disproportionate share of the commissioned officer corps relative to military officers as a whole.
Military officer veterans, despite making up a minority of all veterans, account for a large part of the partisan skew of military veterans after controlling for age, gender, race and education.