The standard is Unicode. The ant is U+1F41C. I have mixed feelings about emojis in the Unicode standard. Apparently this is a Unicode character 'PISTOL':
Sometimes you gotta break a few eggs to make change …
IMHO the 'correct' solution, if you want to remove the handgun picture is to remove it from the emoji keyboard (and possibly refuse to render it) and introduce a new water pistol emoji.
It's an er, interesting position that the emoji standards committee (if that's the term) finds itself in. Do they have the right to determine discourse? There have been small riots (if that's the right term) about skin colors, genders, family composition, jobs, and now about weapons as well. They have the job (which I don't envy) to design an international language that is able to express a lot of concepts and emotions on the one hand, but on the other not to offend if possible.
And then there's the implementers, who have to add an extra layer to it - like the Apple crash bug which was caused by a certain flag emoji being available in one country but not the other.
Why is their job to avoid offending anyone? Why a pistol emoji showing a real life pistol is offensive on itself? It's not like I can't offend anyone using only the ASCII character set.
Emoji are a vital part of the way we communicate online so some see them as a prime way to push their agenda.