HonsterBlungoBenroadsStarted messing around with this stuff again and found that you could remove the muzzle flash that is shown when using viewmodels.
https://www.youtube.com/watch?v=AB_-3rP64n8
I did this by replacing whatever was set to "MuzzleFlashParticleEffect" with "env_rain_001_mist", I chose this because I am fairly sure that it gets tagged as a weather particle so it will not render if you have disabled weather effects (I would assume most people do). It seemed to work with most weapons, the only major exceptions really being the miniguns and a few scout primaries. This all should work on sv_pure 2 and includes my updated explosion stuff.
Download: http://puu.sh/kYAcw/ec207f99a8.rar
anyone got a working version for dx9
Short answer: "nutsnbolts_repair" and keep an eye out to make sure it doesnt cause anything fucky like env_rain_001_mist. Also that download in the quoted post has objects.txt which increases teleporter costs so if youre going to use that download edit or delete objects.txt.
I tried nutsnbolts_repair on a local server and saw no visual particles and didnt notice my frames dropping or anything so hopefully it works. Also personally I wouldnt remove sniper's muzzleflashes since his hitscan leaves no tracer.
Long answer: To more easily test particles I extracted the particles folder from tf2_misc_dir.vpk and launched TF2 using the -tools launch option. Once its launched go to Tools>Particle editor then use Open to navigate to any of the .pcf files you extracted. This should let you see the multiple particle effects in each pcf. I just looked for some that appeared to have no visible effect, FYI for some reason some look like they have no effect in the editor but actually have an effect in game such as bullet_tracer01. Restarting TF2 to test is slow as fuck so this helps minimize that as much as possible when looking for a suitable particle effect.
for dx9
https://www.dropbox.com/s/qv9x6vj92btzohn/nomuzzleflash.zip?dl=0
custom/my_custom_stuff/scripts/