I don't know what the above sniper is talking about. The other tips are good, but the advanced sniper rifle PWNs. It has only 3 shots in a magazine and takes longer to reload, but 2 is all I need to kill. Normally only one, two if the target is moving. I own with a sniper rifle.
And you say that it takes two shots to kill with the Zeller. How many shots do you think it takes to kill with the Moretti/Park. Amazingly it is also two. . But headshots are both one hit KOs for both snipers, but the Moretti/Park has two extra bullets. Doing an extra 15-20 damage by giving up two bullets per magazine is NOT a good trade.