No, it really doesn't - at least among those of us who took basic English in school. We don't say "pissie" for pistol, or "revo" for revolver or "riffy" for rifle...................
There's nothing that makes us look more immature to those from the anti sides who lurk on boards like these than to sound like you are some 9 year old playing COD
So now we have the paranoid fear to the unknown and mysterious anti lurkers and how we might appear to them based on use of "shottie" and other such terms?
If instruction in basic English is the crux of your argument, then please school us on where in basic English it is said that the use of nicknames or monikers must be avoided won't you. The only such rules that come to mind are those that refer to formal dialogue, but only then when such names have not become conventional. I don't believe TFL requires such high falutin dialogue.
However, I have noticed from some of your posts that while you don't like shottie, you are perfectly fine with shortening the word picture to "pic."
Or referring to water moccasins as "water mocs" and alligators as "gators."