You Tube took down this video (under the Future Weapons entry) I removed the link, but if someone has a new example they can relink it. http://www.youtube.com/watch?v=28kRjCFs8fQ#t=0m55s

For the Anime/Manga Section

Angel Beats - has the main cast carrying and using firearms.. Handguns, Assault Rifles, Sniper Rifles, heck even a Rocket Launcher!

http://www.imfdb.org/wiki/Angel_Beats!

Puella Magi Madoka Magica - How can we forget about Homura Akemi!? (And possibly Mami)

Homura using a handgun,shotgun,heavy machine gun, mortars, an RPG, and even a giant Missile etc etc.

Mami's Muskets.. lots and lots of muskets..

I don't know where this would fit in but I'd like to submit this (or have someone else, I don't care for credit):

There's someone on youtube who uploaded a series of Japanese videos that are minute-ish long clips of guns, with specs, someone firing them, and in slo-mo. Some even have porn music!!

http://www.youtube.com/user/Kafkanishian

What category in gun porn would this go under?

No Western Animation ? There are quite a few cartoons, even children's, with robots or mechas armed to the teeth, such as Robot Boy, The Centurions and so on. Does this trope apply for them?