Old game warden who was stationed down in the area of south Texas where we hunt, his "go to" nilgai rifle was a Ruger #1 in .220 Swift.
K W -
I know the 22s kill deer reliably. It's just that for "YEARS" it was against the law to hunt deer with anty caliber smaller than .24 Back then the only bullets for the 223s were varmint bullets and were unreliable performers.
With that 'concrete' foundation and poor performance from larger cal. c/c bullets it's HARD for me to have enuff confidence to TRY 223s today.