I killed 6 deer or so with my 223s one year as an experiment. I was shooting 60gr Nosler Partitions (handloads to max load). I only had 1 deer that showed signs of being hit (rest ran about 100-200 yards an just fell over). Then I decided to switch to head shots on does and they all dropped in their tracks The ranges varied from 75 yards to 250 yards.

So, yes the 223 will get the job done if the shot placement is good.