"It'd be so loud and booming with noises, I'd plug my ears with handgun gestures."
eh?
Hmm.
Would I understand it? Yes, although it snagged me just a little at first.
Would I like it? That depends.
As somebody's dialogue or deep in somebody's POV, it actually bothers me. On its own, "gestures" just isn't a commonly used word (at least not with the folk I hang with or TV people), so adding "handgun" in front of it makes it even more off and awkward to my ears. Most folk I hear speaking, etc, would just stick with "I plugged my ears". Does that mean your character cannot get ultra specific and use words you don't hear quite so much? Not at all. But just letting you know, out of the blue here without knowing anything else about the character and how they speak, it strikes me as being awkward and unreal.
Also important and lacking in the context for us above is whether or not the "handgun" shape of the gestures is important or just there for flavor. If it is some greater importance than merely picturing for the moment a touch more precisely the shape of the plugging fingers (aka, some bit of literary significance or whatever), then I am merely missing the appropriate context above ot make that clear and might react differently with it there. If it is just for the picture, though, then it still strikes me as unneccessary and awkward.
So, like I said above, it depends.
Just my opinion, though.
-Michelle