I typically use "firearm", "rifle", "handgun", "shotgun", "revolver", "1911", or directly refer to the make and model e.g. "Sig", "Kimber", "XD", etc. with one exception (listed below).
I try to avoid words with negative (or loaded) connotations like "weapon", "Glock", and "assault". I don't use "pistol" just because I've never liked it (no logical reason. . . just a pet peeve.).
Similarly, I intend to "stop a threat", not to "warn", "injure", or "kill".
Words matter.