If you go to www.brickarms.com they have increbidle LEGO guns!(do not be discouraged by the prices($2-25 cents), they are AWSOME!!!
Another website is www.brickforge.com, which makes guns as well as other minifig acessories.
A Machine
You can try Brick forge here is the link http://www.brickforge.com/ and that's it
LEGO and brickarms are not connected, but brickarms makes their own LEGO guns that are compatible with LEGO especially the minifigures.
They either buy it seperately or from a Lego set.
Only Space Rangers have guns.
You will have to hunt around for custom army Legos as Lego themselves do not make modern day warfare sets. You should be able to find Lego army men, guns and sets (or just instructions) for vehicles like tanks at websites like Ebay and Amazon.
guns
twin guns and sweet moves
You would go to Brick Arms.com. They selll awsome Lego guns and minifigures
Right now the Taj Mahal and secondly, Millennium Falcon. The Taj Mahal has over 5,000 pieces.
That's an opinion, but from my perspective it would be either Zazinombies, mydifferentusername and Streaty121(makes shooting LEGOS). Hope that helped you out but really your question is an opinion.
Well I say use a nail file.