...there are three particle system effect
Code:
"dxhr_sniper_rail_blue"
"dxhr_sniper_rail_red"
"tfc_sniper_distortion_trail"
then you need set, origin start position..
And "control point" 0 as start position, "control point" 1 as end position.
Code:
m_vSortOrigin = startpos
I have not tested... I just quick peep some source files...
*edit
There is no "tfc_sniper_distortion_trail", maybe it exist in Team Fortress Classic. Actually, there is. Also "tfc_sniper_distortion_trail_noise"
But there is more sniper rail effects, you can look through Hammer editor.