made it to round 33 on survival resistance I thought (yes it was with a friend).
best things you can buy in survival are the assault rifles c-4 for the juggernauts (or a predator if you prefer that).
I don't really exactly know how I got to that wave hahaha.
when playing multiplayer you should take the assault rifle (first one I thought not the 3 round burst) and you can get pretty much kills with that one. For snipering you pretty much found out I see but most maps are hard to scope on.
good luck