I think there needs to be a complete overhaul of both weapons and ammo. I'm a big believer in soft point ammo and use it almost exclusively over polymer tips with the exception of a couple cases, mostly because I like the challenge of having to be precise with a shot and the thill of tracking something down. But also partly because I feel they're very neglected and need someone to love them. That said, on the topic of the .223 still not being buffed enough, I agree. It's better than it was before, but with the .22-250 now in the game, I can kill better with its soft points than with the .223's polymer tips, and I know a difference of 8 penetration isn't a lot, but it speaks volumes about how unbalanced a lot of the weapons are.
The .270 polymer tips have 35 penetration and, in my experience, kill class 7 and 8 animals a lot better than the 40 penetration of the 6.5mm polymer tips. But it's not just the .223 and 6.5mm that feel unbuffed... the .300 and .308 polymer tips have the same penetration and only 1 difference in expansion (13 vs. 14) but one is for classes 4-8 while the other is 7-9. I know IRL the .300 round is bigger than the .308 and does more damage, but just the stats/ratings alone in the game don't tell you that (except for the integrity numbers).
It seems to come down to which rifle has more punch or boom than another, and for something to have the same stats as something else but perform magnitudes better seems unbalanced to me. Especially without a stat or rating of some sort to tell you how much boom something is going to have. The M1 seems to have more boom than the 30-06, in my experience, but it uses the same exact ammo, not even a different ammo that's comparable. But just looking at them doesn't tell you that.
So I agree with the .223 and 6.5mm still needing to be reworked, but I also think the entirety of the ammo stats, weapon stats and class ranges need a complete overhaul.