I am wanting to get the damn joker skin for completing all the humilitation challenges, but there is one challenge that will not allow me to complete! Forgot what its called atm, but its the one that says something like "pick up a weapon and get 5 kills without dying using only that weapon".

I have done this a handful of times on hardcore FFA and also HC TDM and it does not give me the unlock.

Has anyone else tried this? If not, will you do so or when you do so, if you can post your results here it will be much appreciated. Going to try different game modes like core and what not... but until then any info anyone has would be great!