Requesting help for weapon effects

Okay,im going to edit discovery 4.86 mod.
all i want to do is to change the impact,muzzle flash,projectile and sound of some weapons.The waepon i want to edit is the mortar,all types(light,normal,heavy).So far i edited the impact effect,it worked,but whenever i edit the projectile effect the game either crashes or doesnt change the effect.I know which weapon is which i am 99% sure,but i might be wrong.
any tips on how to edit these effects please?
try to anwser ASAP please,i need this fast

THX alot in advance