No gun ever caused anybody to commit a wanton killing.
Many many people have misused guns to commit wanton killings. But others have used them properly, to guard and defend what ought to be guarded and defended.
Funny how the people seemingly so interested in root causes can be so shallow here. And any house of Christian faith should know that you don’t blame inanimate things for situations where humans accept the work of demons!
I don't understand why the Archdiocese of Chicago tolerates him. I believe the late Cardinal Francis George suspended him (very briefly) from his pastorate a couple of times, but he has never been effectively disciplined, let alone transferred or laicized.
I think it's fair to say that the present Archbishop of Chicago, Blaise Cupich, doesn't really give a flip that heretics control whole parishes in Chicago.
Perhaps we ought to keep in mind that Fr. Pfleger's foster son was killed by random gunfire in the street maybe 15-20 years ago. That may explain his stance against guns. He has principally campaigned against violence in the high-crime neighborhoods of Chicago, tried to drive drug dealers, gangs, and pimps out of the area, forcefully criticized gangsta rappers who glorify street crime and the sexual abuse of women ("hos" and "bitches"), and worked hard to clean up his own neighborhood.
The link above gives a lot more background.