Idk man. I think we were playing on Normal and even that was somewhat hard. Its tough to say though because with 5 people itd be alot easier (we only had 3 people). We played on mansion and when we stayed up by the sniper it was easy but when we went outside we got owned. Also everyone respawns at the end of each wave and if you die you can start over from that wave you were on. So I mean eventually yeah anyone should be able to get to 50, just depends on how long it takes. Either way its a blast though. I can't wait to get home and do some more coop though, i want to progress the story.