Lukers,
Welcome to the forum. Please read the stickies at the top of the forum, especially in the Models and Media section. Lot's of good info and links to content there.
Any basic modeling program will make guns. Animating, texturing, and getting the FPSC ready is just going to take time and practice. There is no magic program, but there are some helpers like
FPSC Toolbox.
At the top of the Models and Media board is a
sticky with many links to free models and media.
fpsFREE and
FPS-Files are good sites for more content.
Brian.