ok, lets assume you are fighting a viable opponent. you wont be able to stand still and dps.
so the dps of the weapon is almost "useless", coz your shots will be delayed anyway.
5dmg scope for everyone (except BoA gun)
bows:
[item]Razor Arrow[/item] or [item]Precision Arrow[/item]
i think you are not farming the precision ones on a horde char and trade them through the neutral auction house right?
[item]Monolithic Bow[/item]
range -> 80,25-125,25 (91-136) [244]
average -> 102,25 (113,5) [221,5]
average dps -> 37,9 (42)
guns:
[item]Solid Shot[/item] or [item]Hi-Impact Mithril Slugs[/item]
slugs are easy to obtain, so i wont do any math for not having them.
[item]The Silencer[/item]
range -> 98-149 [261]
average -> 123,5 [235,5]
average dps -> 44,1
[item]Shadowforge Bushmaster[/item]
range -> 100,75-151,75 [267,75]
average -> 126,75 [242,75]
average dps -> 43,7
[item]Sniper Rifle[/item] (of marksmanship)
range -> 117,5-130,5 [250,5]
average -> 124 [244]
average dps -> 41,3
[item]Upgraded Dwarven Hand Cannon[/item]
range -> 97,5-148,5 [264,5]
average -> 123 [239]
average dps -> 42,4
as you can see, every gun is superior to the bow, even if you start farming the dmn arrows.
i'll add some numbers in square brackets now...these are the numbers with additional 40dps (560AP).
now you can see that bushmaster grants the highest dph, but has a wide range. sniper rifle has a small range and grants the highest average dph. depending on situation one of these two is the BiS weapon.