tutorial:
your .qc configuration find anims $sequence puts only fire animation for (fire01,fire02,fire03,fire_last,Fire_Iron1,Fire_Iron2,Fire_Iron3,Fire_Iron_Last) WARNING DONT PUTS ON Fire_dry and fire_iron_dry because is out ammo animation.

how to puts new muzzleflash: you need puts new events:
{ event AE_CL_CREATE_PARTICLE_EFFECT 0 "(PARTICLE NAME) follow_attachment (ATTACHMENT NAME)" }
this is your puts on sequence animations EXEMPLE:

}

$sequence "fire01" {
"v_fa_fnfal_anims\fire01.smd"
activity "ACT_VM_FIRE" 1
{ event AE_CL_CREATE_PARTICLE_EFFECT 0 "assaultrifle_small_flame follow_attachment muzzle" }
{ event AE_CL_CREATE_PARTICLE_EFFECT 0 "weapon_muzzle_flash_smoke_small2 follow_attachment Eject" }
{ event AE_CL_EJECT_BRASS 2 "308 Eject" }
fadein 0.2
fadeout 0.2
node "Fire"
snap
fps 30
}

PARTICLE NAME:
>Muzzleflash X:
"assaultrifle_small_flame

>SmokeShellsEject:
"weapon_muzzle_flash_smoke_small2

>BigSmokeSniperOrShotgun
"shotgun_smoke_oldstyle

>SparkShot:
"shotgun_sparks_2

>ShotgunOverhaul:
"NMRIH_SHOTGUN_FLASH

>Revolver357:
"NMRIH_357_FLASH

>MuzzleFlash AK74 Break:
"ak_muzzleflash