Is it me or is stage 5 just obnoxiously tedious and intentionally lengthy? It seems they want to punish those of us who did not purchase the DLC so we'll pay to skip the nonsense grind. I mean 100 open world mounted gun kills, come the F on! 50 mounted gun kills on Roosevelt Island, well with all the enemies focusing you, how could this end badly? If I ever finish it, this specialization better be the **** due to the nonsense your putting me through. Of course this might cause me to just stop playing since I can only imagine the next specializations will be more of the same ridiculousness and its just too much, for me at least.
I've also seen that animals count towards the total... not that I'm suggesting anything.
I personally enjoy these sorts of challenges that require playing the game a different way/focusing on a divergent method than usual. Where along in the challenge did you first start to feel like it was becoming a tedious slog?