[Yithian]

I use a 204 for deer.
Bullet selection and placement are key.

I use 40gr Hornady V-Max and head shots.
Turns deer heads into sacks of rocks.

With that small a caliber, you must ensure a quick and deadly hit, every shot.
To use a fmj or soft-point would be too risky.
Use "grenades" at MACH 3 or greater for 223 caliber and under, and scramble that brain.
The best head shot is when the deer is looking away from you and upward.

It requires patience, speed to acquire, and timing.
A rule of thumb:
If a deer is wary, the head will not stay still long enough.
If you are not comfortable with shots at your ranges, to hit possibly moving heads, don't even attempt it.
Go for larger calibers and boiler room shots.