sry, no sniper script, thatd probly be pretty hard to make, as theres just limitations in the ofp engine, for example, you just cant make a soldier reliably hit a target 100 percent of the time. ive heard about oem sniper scripts floating around, well, at least on the old forum, but, thats all in the past. i think it also be difficult to make a "universal" sniper script, one thatd fit any sniper situatin.
since almost every sniper encounter is different (urban sniper, one shot kill sniper, cinematic sniper) itd be very difficult to make a sniper script to suit every one. an urban sniper would not be effective (or realistic) at all in a open country situation.
its best just to custom tailor it within the in-game engine, such as using triggers to detect if a playr is in the "kill zone" and the sniper will only fire at peeps inside the killzone, thus not giving his position away.
remember, if you give an ai a "guard" waypoint, and put him in either combat or stealth mode, hes gonna bea lot more effectiv/ sniper like, cuz hes gonna utilize his ai better (does stuff like search out teh enemy, man empty mg guns)