Playing Sniper in Mann v.s. Machine is a pretty drastically different experience than that of playing the class in a standard game type. This is due to the sheer number of enemies. Doing a lot of damage to a lot of enemies is a greater aid to the team that the Sniper’s extreme precision. Especially when fight a wave with robot scouts, the sniper can be easily overwhelmed by the number of targets to be really effectual. For this reason it’s more helpful to the team to play that class in more of an assist role.
The best way to do this is with the jarate. The jarate’s splash damage of kits is perfectly useful in this game mode in all the ways the rifle wouldn’t be. Since this is a teamwork heavy game type there is no pressure to get the kills, one of your team mates can do that. Jarate just does a great job of making it easier for them. Its an item that is useful anywhere where there is a cluster of enemies, which is almost all the time. My personal favorite is when their is a bunch of medics following a giant robot. What once was an unstoppable mass falls pretty quickly when their whole group is taking crits. Because if its usefulness, maxing out the upgrades on the jarate is a great move. Especially the recharge rate, which when maxed only leave a half second of waiting between tosses. This is great because the one annoying aspect to the jarate it trying to find somewhere to hide/something to do during the recharge time.
Unfortunately none of the sniper’s primary weapon options are really useful in the mvm game play. The best case that I could find was using the bow and arrow. The since the bow didn’t need to scope in I felt i could do more damage to multiple targets, and I could keep a better eye on my surroundings. Unless you have a teammate who is specifically protecting you, your going to appreciate this this greater field of vision as the robots quickly become so numerous at points that they can’t help but be right next to you.Another benefit of the bow is the upgrade for it that causes bleed damage. This also help in the sniper’s support style of play, as as long as you hit the target once you’ll be doing damage to him for a while. This will give your teammates a chance to finish him off.
Article from Gamersyndrome.com