Sorry folks, but no sniper in his right mind will use a laser!
Y'see, by the time a laser's power density (watts per cm^2) reaches
levels useful in a weapon, it has reached levels that will cause the
air to ionize along the beam path. I can show you a lovely picture of
an IR laser beam in the air of a lab. Looks like something out of a
special effects crew's nightmares.
No intelligent sniper is going to use a weapon that draws a line
connecting him with his target!!
You want quiet, hard to detect in weapon scans, lightweight, and
*deadly*? Just the thing here. A crossbow! They've been used as
recently as Vietnam. And with a composite material for the bow, it's
invisible to metal detectors and explosives sniffers. And it has a
decent range. A few hundred yards at least.
Thunk!
"Sir, they got the Colonel! Some sort of arrow... Arrgh!"
<crackle> "HQ? Hello? hello?" <crackle>