Like T Inman, I have seen several killed with 223s (deer too)
With 60 grain Hornadys and 65 grain Sierras the results were mixed. Mostly good, but both bullets break up and sometimes don'rt penetrate well. However with 60 grain Nosler Partitions and 62 grain Barnes the results were excellent in every case.
I have about 40 rounds loaded with 60 grain partitions myself, but as of now I personally have not killed any deer of antelope with my 223s. Not that I wouldn't. I expect I will sometime in the not-too-distant future. But I seldom leave Wyoming anymore for hunting, so I only kill 6-8 deer or antelope a year now, and for the guns I want to use, and the bullets I want to try I have set my 223s in that list, but I probably won't get to them for 2-3 more years.
I have witnessed about 10 kills with this bullet however, so I am 100% confident in it's abilities for deer and antelope hunting and any shots out to about 350 yards.
