Barney stuck in Following Freeman

[PinkFluffyLlama]

I am in the warehouse with Barney on the roof. He says to lob a couple of grenades to take out the snipers. At this point I have already killed both snipers. I took out one before entering the building, and the other right before finding Barney. I have lobbed a grenade into every window I could find, but Barney doesn't budge. Am I supposed to kill the snipers after I talk to him or is this just a random bug?

[jawbreaker684737]

You have to go up on the roof and stand next to him for the new snipers to spawn in the formerly empty windows. I spent an hour and a half lobbing nades into empty windows untill i figured that one out...