To all of those who think the .204 is not a round to be shooting in the wind, you should check the ballistic coefficient of the 39 gr. bullet and compare it to the 53 gr. .223
Believe it or not, they shoot better as they have a lower ballistic coefficient and are able to shuck the wind better.
I shoot both rounds and I don't worry about the wind with either round. It is all part of hunting. The wind will blow your 120 gr. .30 cal bullet further off than either the .204 or the .223 It is all about knowing your rifle and ammo.
actually...you want a HIGHER ballistic Coefficient in high winds.
A bullet with a high BC will go longer, faster, better than one with a low BC since it will retain its velocity better. and it will do better with the wind....BUT ITS NOT THE ONLY FACTOR...a higher BC does not mean better wind res ALL THE TIME.
204 vs 223 from a BC point of view will depend on how its loaded and with what. 223 gives more flexibility in my opinion, so thats what I would go with. I don't imagine you'd see a huge difference between the two performance wise...so I'd go with something practical.
the highest BC i can find for a .204 is about .295 (50gr hpbt)
the highest BC for 223 i can find is .511 (90gr HPBT)....not commonly factory loaded...but if you do your own it's feasible. these are what some of the guys i know use for shooting in NRA High Power matches with AR15s. they have to loaded singly into the rifle because they don't fit the mag! I stick to 77 and under on my match gun since they fit normally.
I've have seen factory loads up to 77gr for .223 which gives a BC of about .372
.223 can be loaded from approx 40gr to 90gr.
.204 can be loaded from approx 30gr to 50gr
honestly though....while i favor the flexibility of the .223 over the .204.....you'll do just fine with either....so don't dwell on it too much