Well,I am not Ingwe but I am almost as old as him.
I have been shooting 223's near exclusively for PD's and ground squirrels since the 60's and have gone through a lot of bullets and barrels.
My better 223's will average 1/2" for 5 shot groups, my more ordinary ones will average 3/4" to 1' for 5 shot groups. In both cases I generally start noticing the odd uncalled flyer, or the groups starting to open up at around 4500 to 5000 rounds. I rebarrel when that starts happening I do not like a rifle that I do not have total confidence in. As far as practical field accuracy I believe that a person could get another couple of thousand rounds of useful life from them and still hit most PD's within 300 yds, on ground squirrels though the miss ratio will go up rapidly.
I do not generally run my rifles long and hot, I take multiple 223's and usually shoot 10 rounds and set it aside to let the barrel cool and rotate to another rifle. Yesterday when I was out I had 4 rifles and number one was just barely cooled by the time I got to number 4. A great day!
drover
