Ah, thank you. I did find Rifle-NG, and located RifleBurst-1-Pulse, in Costumes, but the problem is that I'm trying to give a different weapon the full effect that the Impulse Rifle gives when firing. I can get the blue tracers to work, but it seems that the actual muzzle flash needs to come from <muzzle_effect> in weapons.xtbl, not from changes in Costumes. The problem is that there doesn't appear to be a <muzzle_effect> in weapons.xtbl for the Rifle-NG. That's odd, since it definitely has a custom blue muzzle flash, plus it throws off blue sparks when you hit something.It's called Rifle-NG and you have to look in the weapon_costumes.xtbl.
The Impulse Rifle costume is called RifleBurst-1-Pulse. When you found it scroll down a bit for all the effects such as muzzle, tracer and bullet impact.
Thanks I'll try that now!What you need is <Effect>Pulse_Rifle_Muzz</Effect>, which is found in weapon_costumes.xtbl
I have also changed the muzzle of the EM Railgun as I'm using this mod and it worked just fine.