check this 1:10. the beam does not come out of the center ceiling-hole.
Edit: Also, the hitboxes of the controllers seem to be a bit off… or maybe they are just a bit small.
the beam, i dont have that problem, and i play hl1 and i noticed who the controller also have the same hitbox in “normal”, you need to shoot the head.
Kinda looks like a Zbuffer problem… my knowledge stops here xd