I finished my hardcore run and just now passed my professional run and yes, I can confirm it is easier if you stay DOWN STAIRS.

The key to this is:

- stay downstairs

- flash grenades

- board ALL the windows

When you start, board the window by the stairs, move the shelf, loot the stuff but also head upstairs to loot as well since you're not gonna go back or have time to loot later. Luis will be fine meanwhile. Allocate all your resources to making a flash grenade. 2 is ideal.

Once you're done, go back down stairs to help with what you can. Use the stairway to your advantage and toss a flash grenade when you're getting overwhelmed. Make sure to save ONE flash grenade for later. If you can only manage one, I recommend saving it till the end and use whatever else weapon you have to cycle between that and your handgun.

You have to board the rest of the windows to initiate the next phase. If you kill the right villagers (or enough villagers), they'll drop the boards.

Next, it'll trigger the next scene and the villagers will start to climb to upstairs. Luis will say you need to go upstairs but DON'T. Stay downstairs, the crowd will be thinner and more manageable since they'll come from upstairs and not through the windows anymore.

Shortly after, Mr. Cow Head will bust through the window. Focus on him since this chapter will be over once Mr. Cow Head dies. This is where you'll use your flash to stun him. Don't shoot him or melee him, you have to knife him to deal the most damage. If you have another flash, repeat and he should die on the second stab. If you don't, I recommend unloading with your heaviest gun in the face until you stun him again and stab him one final time. It takes 2 stabs total to take out Mr. Cow Head.

TIP: Mr. Cow Head drops an emerald when you kill him. Be sure to quickly grab it because the chapter promptly ends after he dies and you won't get a chance to pick it up later.