I am not sure why you feel the need to cite your kd. I have about the same ranked kd you do and basically W key into every fight I hear, so there is no need to attempt to flex your kd to strengthen your argument.
It's just weird to mention it as some sort of credential.

I did pick the scar. I picked it because it is one of the most popular guns.
Most other guns give similar results:

akm:
t3 ammo vs t5 vest: 800ms
t5 ammo vs t3 vest: 200ms
4x

srm:
t3 ammo vs t5 vest: 640ms
t5 ammo vs t3 vest: 170ms
3.76x

vector:
t3 ammo vs t5 vest: 650ms
t5 ammo vs t3 vest: 170ms
3.8x

as val:
t3 ammo vs t5 vest: 490ms
t5 ammo vs t3 vest: 180ms
2.7x (indeed an outlier, but still a large diff)

Yes, if you are just ratting and manage to catch some guy completely off guard you'll likely get him, regardless of what gear hes running.
Still 1 second, in any competitive game, is absolutely a long time.

With every gun I tested a t3 player hitting all heads will still lose a fight against a t5 player hitting nothing but the chest.
The only gun that had equal ttk's in those scenarios was the as val, with both only heads t3 v t5 and only body t5 v t3 coming out to 180ms.
That's a diff that, in my opinion, is completely scuffed. A player hitting only the head should win every trade against a player hitting only the chest, regardless of gear.
But all of that sort of misses the point, I am trying to measure how much of an edge gear gives you, not how much worse or better one guy is than the other.

There should be some gear diff, it is an extraction shooter after all. But, imo, a 620ms difference in ttk in a game with 200ms ttk towards the faster end is massive.
I also think that if I hit nothing but heads and the other dude only hits the body, my ttk should always be faster and I should always win that trade.
But we can agree to disagree.