I'm not really sure how to do it, but I'm gonna try and shoot the scenes, and then make a 3ds max animation with muzzle flashes.. there should be some tutorial somewhere, and mix these together, either with bluescreen (blue background in 3ds) or render the animation directly on the footage..

Let me know if you make a good result..

http://csnation.counter-strike.net/morph/tut_muzzleflashesin3dsmax.php

Check this one out! 🙂
Pretty neat!

i was trawling for info on bullet effects and after about 4 days of looking in my spare time i found this gem of a site!

http://deathmonkeybdm.tripod.com/deathmonkey/id17.html

I found it really useful for its tutorials on how to do slide movement, muzzleflash and casings in photoshop
only photoshop (or a similar program such as paint shop pro by Jasc) is needed!

Syras