I don't really know what a sniper map is (because I snipe on all maps) but these are the maps that I see most people using sniper rifles.
Destroyed Village (turns into MG/SMG bout with CKR on)
The Hunt
Das Boot
http://www.alliedassault.com/pafiledb/p ... ile&id=880
LOL V2
http://www.alliedassault.com/pafiledb/p ... ile&id=965
Some people use snipers on the Bridge too