I dont know about any aim-bot but I have seen some stuff that lends to the possibilty, for instance
I no longer use GVs because the last time I did, I hit an NME panzer 4 times(out of 12-15 rds fired) from very very long range while he was moving & I was stationary. Not only did the panzer prove to be teflon coated but he killed me in 1 shot while he was moving. Needsless to say I have NEVER taken a GV out again, nor do I have any intetion of doing so.