I have created bullet tracers for my gun in Roblox. They are not good, though, as the bullet tracer(s) will take time to apply velocity with the linear velocity. I also do not know how to make the tracers stop when they reach the position of the raycast.
Video of bullet tracer delay:
Code:
-- firepos is gun fire position, "Parent" is the tool, "Position"
-- is raycast position, "Debris" is workspace folder
local tracer = game.ServerStorage.Tracer:Clone()
tracer.Position = Parent.FirePos.Position
tracer.CFrame = CFrame.lookAt(Parent.FirePos.Position,Position)
tracer.Parent = workspace.Debris