Nothing but headshots on Vall stage problem

[NillaWafer]

I've tried using headhunter and death & taxes with the mouse gun. Everytime i beat the stage the game says I only had a 95% headshot rate, but to my knowledge I haven't missed a headshot yet. I've done this stage dozens of times, all with the same 95% headshot rate, and it's driving me insane. I have no clue wtf I'm doing wrong

[Pan Puszek]

The "only headshots" thing refers to "Vall's nest" which means you need to take only headshots AFTER you take the sniper rifle at the end of the level. Up to that point you can have 0% headshots.
Remember you need to kill with headshots every monester in her nest, not only her. In fact you need to kill her last because killing her ends the sniping sequence.

[14 legs $10]

Also, I find that the burst gun demons have wonky hitboxes, so headshots made while they're crouching might not count randomly

[The Notorious G.R.D.]

A few tips.

Don't risk a head shot on a crouching demon. It happens more often than you'd think that they get up right as the bullet is about to hit their head. Just don't risk it.

You can shoot the wall as many times and it won't count as "not a head shot" this makes shooting those freaking patrolling dudes MUCH less tense.

When it comes to the burst rifle demons, aim for their horns to be safe. If you miss and hit the wall,no harm done.

Shooting lights or another enemy can halt a patrolling guy long enough to manage a shot on them.

Take your time. You have all the time in the world. Take your time and carefully line up your shots.

Good luck!

[Husum]

Also
There are 5 demons on the roof, one big guy patrolling and 2 guys at each edge, I didn't see them at first and it drove me nuts.
Additionally, if you spook the demons, some of them will try and escape via the elevator. Don't let this happen or you will forfeit the achievement.
However it does make for an easy headshot, as the escaping demon will stand still and wait for the elevator to arrive.
Happy achievement hunting!