i have used a 223 and i had an uncle and his friend both use a 223 this yr. in fact his doe he shot droped faster than the buck i shot with my 30-06 with 165 grain. i hit in the just behind the heart. he hit the heart. droped the deer my buck ran(or should i say stumbled) 5-10 yrds. like pahunter86 said just depends on the accuracy