IMO: The title..."Elk and the .223.Why not?" Answer..In several states it is not even legal and it is a small bore designed for varmints or wimmpy creatures like humans. The body of the post..if a .243 is an elk killing machine why not the .223 etc.etc.. Answer..if the .243 was an elk killing machine then you could make that argument..if a 22-250 is a coyote killing machine, then why not a .223, then why not a .222, then why not a .22 hornet, then why not a 22mag, then why not a 22 lr and i'll skip the 22 long and just get right to the short ! No SERIOUS elk hunters think a .243 is a elk killing machine. If a .243 was and elk killing machine then yes, why not the .223 ? Let me know when we get down to the .22 short cause it will kill and elk also, likely even fronm a 2" snub nose pistol..go right through the orbitable socket just so the odds will make it better for a clean kill if thats a consideration..
