Gun-Centered Anime

I realize this might be a bit of a stretch but, my search criteria are rather specific.
I am looking for Anime that have guns (realistic guns (Not a fan of sci-fi/future weapons) as a strong point. Also, i would really rather it is plot driven in a more serious/mature fashion rather than a "Hey look! a girl with big bouncy boobs is shooting a gun!" (Blasphemy, I know). I have watched and enjoyed shows like gunslinger girl, trigun, Black Lagoon, cowboy bebop, canaan, FMA, jormungand (though that was a little more on the ecchi side), and ghost in the shell.

If you have any suggestions, they would be greatly appreciated.
Thanks,
Ephemurai

Try This Golgo 13

hidan no aria and black bullet

Thank you genjuro, Golgo looks pretty cool, so i will be checking that out.
Thank you Yondaime, i have been watching black bullet, but not Hidan no Aria, and it looks pretty good so i will check that one out as well.