We should make a distiction here. There are medical doctors that are psychiatrists. They study the medical diseases of the brain. Most, but not all, also use pyschology.
A pyschologist is NOT a medical doctor. It is amongst the pyschologists that most of the quacks reside, and it is the pyscologists that are primarily the socialists. Pyschologists are the social workers and such.
Of course, not all of them are that way, many are good serious folks who truely want to help people, but there a huge number of socialists in their ranks.
My rule of thumb is: most people that are interested in pyscology are interested because they want to find out why
they are so messed-up (we all are in one form or another, so this is understandable). When you take that to the PhD level, that really tells you how messed-up they are
I took a couple of senior level psy classes as an undergrad. On of my professors was great. He explain right from the start that pyschology was a pesudo-science. That while many good psychologist tried very hard to apply scientific principles to their studies, the complexity of humans made it nearly impossible to truely do this. That was a very interesting and very well done class--Human Growth and Development, if I recall.
Back on guns, most of what I have seen about anti-gun stuff has been from the AMA medical community. They are looking at, and want to deal with, the gun violence (primarily from gangs) as a medical problem. IMHO, they are simply applying their hammer to a nail they see (even though it may really be a screw).