AEG snipers observe the AEG limits.
Bolt action operators are, with field owner and hosts discretion, given a slightly higher limit.
With AEG's, even with your selector locked to semi, it still allows for a follow up rounds to be fired too quickly.
Snipers shots are typically deliberate single rounds and shouldn't require too many follow up shots to make a kill. the more shots you take, the quicker they will find you. AEG's are inherently loud and are not the best tool for a sniper.