okay fellas,
im not talking about the disclaimer on a box of ammo that states may be dangerous up to a couple of miles.  i am talking about how far can one using match or better ammo and a solid setup maintain moa accuracy?  what type of bullet wt are being used, hand load, etc....  some guys are saying they are maintaining that type of performance upto 700yds with heavier bullets.  of course they didnt specify conditions etc, just that it has been done more than once..  
thanks,
jimmy

once begun, halfway done.

If you are talking .223, the heavier open tip match loads are what you want for long range accuracy. There are many choices out there with one of the favorites being the loads using 77 gr bullets from Nosler and Sierra. There are also designs using 68, 69, 73 and 75 gr bullets that offer good performance. With the right gun and ammo and if the shooter had the ability (this is the key factor), then 600-1000 yard shots isn't outta the question for accuracy. Think of matches such as those at Camp Perry where long range shots out to 1000 yards are common. But keep in mind that at such extreme distances the .223 isn't gonna be capable of doing much damage. At ranges such as that, a good .308 setup using the 175 gr Sierra MatchKings rule the roost.

-Charging Handle

Agent:  Used a m16-A1 in the 80's, could keep it minute of man at 500 yds with ball ammo.  Hooker rifles, too.  Everyone in the neighborhood had their hands on it one time or another.  Good match rifle, match ammo tuned to rifle, 1,000 yards should be no problem.  Will also concur with damage estimates at that range.  Want to put a hole in the paper, cartridge has little significance.  Put the hurt on, .308 or better.   Just my $.02.

thanks for the responses.  even if the shooter had a perfect day and the gun ammo combo was right on how much stability would the heavier 75+ grain bullets have over the lighter stuff also how about against the 308.  tried do a search on the difference of 223 heavy vs 308 and didnt find too much.  i love shooting .223, and am considering working up a heavy wt hand load or just getting a 308.  dont forsee taking down any game at over 800yds but would like to knock down steel pigs at that range or better.  so give me your feedback.  thanks again

well i guess that does it.  thanks ar15.com and people that replied.

Is this the thing about a sledge hammer and a gun might both have the same energy, but the sledge hammer knocks something down when the bullet doesn't?

Is this because when the bullet hits the steel target, all of its force is expended at a high rate of speed and at this high rate of speed, the steel target appears immovable to the bullet.

Water is very hard if you hit it fast enough.

Very light things can appear heavy when they don't want to get out of the way fast enough?